UNIT-IData communications

Short Answer Questions:

1. What is data communication? List types of data communication.1A. Data communication is the transmission of electronic data over some media. The media may be cables, microwaves or fiber optics. Types of data communications are

- Point to point communication- Point to multipoint communication

2. Write various modes of data transmission.2A. There are three modes of data transmission1. Simplex mode.2. Half-duplex mode3. Full-duplex mode.

3. Define bandwidth.3A. Bandwidth means the amount of data that can be transferred from one point to another in a given time period (usually a second). Bandwidth is usually expressed in bits per second (bps) or Bytes per second(Bps).

4. List various communication channels 4A. 1. Coaxial cable 2. Twisted pair cable

3. Microwaves 4. Fiber optics.

5. Write various methods of data transmission5A. Synchronous transmission

Asynchronous transmissionIsochronous transmission

6. What is Isochronous Data Transmission?6A. An isochronous data transfer system combines the features of an asynchronous and synchronous data transfer system.

7. Write various forms of Data Transmission?7A . There are two forms of Data Transmission

1. Analog form2. Digital form

8. What is parallel and serial interface?8A. A parallel interface refers to a multiline channel, each line capable of transmitting several bits of data simultaneously.

A serial interface uses a serial port, a single line capable of transmitting only one bit of data at a time.

9. What is multiplexing? Write various types of multiplexing.9A. Multiplexing is a technique of simultaneous transmission of multiple signals over a single transmission media. Various types of multiplexing are

1. Space-Division multiplexing (SDM)2. Frequency-Division multiplexing (FDM)3. Time-Division multiplexing (TDM)4. Code Division multiplexing (CDM).

Long Answer Questions

1. Explain various types of data communications.

1A. There are two types of data communications

1. Point to point communication2. Point to multipoint communication

1.Point-to-Point Communication: point-to-point connection refers to a communications connection between two nodes or endpoints. An example is a telephone call, in which one telephone is connected with one other, and what is said by one caller can only be heard by the other.

2. Point-to-multipoint communication: Point-to-multipoint (PMP) communication refers to communication that is accomplished in the form of one-to-many connections, offering several paths from one single location to various locations. Point-to-multipoint is generally abbreviated as PTMP, P2MP or PMP. Examples of point-to-multipoint communications systems are radio and television broadcasting.

2. Write about transmission modes

2A.

Types of Transmission Modes

There are three ways for transmitting data from one point to another

1. Simplex2. Half – Duplex 3. Full – Duplex

1. Simplex: In simplex mode the communication can take place only in one direction. The receiver receives the signal from the transmitting device. This mode of flow of information is Unidirectional. Example: Radio, T.V., Pager transmission.

2. Half-duplex: In half-duplex mode the communication channel is used in both directions, but only in one direction at a time. Thus a half-duplex line can alternately send and receive data. Example is the wireless communication.

3. Full-duplex: In full duplex the communication channel is used in both directions at the same time. Use of full-duplex line improves the efficiency as the line turn-around time required in half-duplex arrangement is eliminated. Example of this mode of transmission is the telephone line.

3. Explain synchronous , Asynchronous and Isochronous data transmission methods

3A. These are all methods used to transfer streams of data. Waveform diagrams can be used to illustrate these different transmission modes. A waveform diagram shows how the signal might appear on an oscilloscope screen, which produces a diagram with voltage on the vertical axis and time on the horizontal axis.

Synchronous

Bits in a synchronous data stream must be transferred in sync with a clock signal. The control signals for the data are derived from a clock signal. Synchronous data transfer systems usually have an error detection mechanism. If an error is detected the data can be resent.

Asynchronous

Bits in an asynchronous data stream can be transferred at random intervals and the data rate of the stream is not required to be constant. Asynchronous systems use a start bit to signal the beginning of a data transmission. A stop bit is used to signal the end of a data transmission. Asynchronous data transfer systems usually have an error detection mechanism. If an error is detected the data can be resent.

Isochronous

An isochronous data transfer system combines the features of an asynchronous and synchronous data transfer system. An isochronous data transfer system sends blocks of data asynchronously, in other words the data stream can be transferred at random intervals.

Each transmission begins with a start packet. Once the start packet is transmitted, the data must be delivered with a guaranteed bandwidth. Isochronous data transfer is commonly used for where data must be delivered within certain time constraints, like streaming video.

4. Explain various types of multiplexing with neat diagrams

4A.

Multiplexing technologies may be divided into several types, all of which have significant variations. They are

1.Space-Division multiplexing (SDM)2.Frequency-Division multiplexing (FDM)3.Time-Division multiplexing (TDM)4.Code Division multiplexing (CDM).

1.Space Division Multiplexing(SDM): It is nothing more than the provision of multiple fixed bandwidth channels by multiple physical paths (i.e., pairs of wires or optical fibers). A good example of SDM is the use of a 25-pair cable to carry the conversations of 25 individual users from the customer's premises to the local telephone company’s  Central Office location.

In wireless communication, space-division multiplexing is achieved by multiple antenna elements forming a phased array antenna. Examples are multiple-input and multiple-output (MIMO), single-input and multiple-output (SIMO) and multiple-input and single-output (MISO) multiplexing.

.

2.FREQUENCY DIVISION MULTIPLEXING(FDM): It is a communications method that allows the use of multiple electromagnetic frequencies to transmit information , thereby overcoming the limitations of a single carrier frequency. To utilize Frequency Division Multiplexing, data must be transmitted separately on different channels. The first , simplest example of FDM is FM Radio with different stations broadcasting at different frequencies called “channels”.

3.Time Division Multiplexing(TDM): The TDM interface enables many devices to communicate over a single bus. A TDM periodically generates a frame consisting of a fixed number of time slots that are constant in length. Each communications channel is allocated a time slot, and it can transmit data only during its allocated time slot(s). If a channel must send more data, it must wait until its next assigned time slot is available. If it has no more data to send, the time slot is sent empty

Consider an application requiring four terminals at an airport to reach a central computer. Each terminal communicated at 2400 bit/s, so rather than acquire four individual circuits to carry such a low-speed transmission, the airline has installed a pair of multiplexers. A pair of 9600 bit/s modems and one dedicated analog communications circuit from the airport ticket desk back to the airline data center are also installed.

4.Code Division Multiplexing(CDM): It allows signals from a series of independent sources to be transmitted at the same time over the same frequency band. This is accomplished by using orthogonal codes to spread each signal over a large, common frequency band. At the receiver, the appropriate orthogonal code is then used again to recover the particular signal intended for a particular user.

5. Explain about various communication channels.

5A. The communication channels are

-Coaxial cable-Twisted pair-Microwaves-Fiber optics

1.Coaxial cable:

These cables consist of an inner copper wire of varying thickness surrounded by insulation and other shielding. Their stiffness caused network administrators difficulty in installing and maintaining thin net and thick net.

A type of wire that consists of a center wire surrounded by insulation and then a grounded shield of braided wire. The shield minimizes electrical and radio frequency interference.

Coaxial cabling is the primary type of cabling used by the cable television industry and is also widely used for computer networks, such as Ethernet. Although more expensive than standard telephone wire, it is much less susceptible to interference and can carry much more data.

2.Twisted pair:A Twisted pair consists of two insulated copper wires typically about 1 mm thick. The wires are twisted together in a helical form. The purpose of twisting the wires is to reduce electrical interference from similar pairs close by. The following figure illustrates the twisted pair (two parallel wires constitute a simple antenna; a twisted pair does not).

Twisted pair is the ordinary copper wire that connects home and many business computers to the telephone company.

3.Microwaves

Microwave communication is a method of transmitting information or energy by the use of radio waves whose wavelengths are conveniently measured in small numbers of centimeter; these are called microwaves. This part of the radio spectrum ranges across frequencies of roughly 1.0 gigahertz (GHz) to 30 GHz.

Microwave radio transmission is commonly used in point-to-point communication systems on the surface of the Earth, in satellite communications, and in deep space radio communications. Other parts of the microwave radio band are used for radars, radio navigation systems, sensor systems, and radio astronomy.

4.Optical fiber:

An optical fiber  is a flexible, transparent fiber made of high quality extruded glass (silica) or plastic, slightly thicker than a human hair. It can function as a waveguide, or “light pipe”, to transmit light between the two ends of the fiber. 

An Optical fiber cable has a cylindrical shape and consists of three concentric sections; the core, the cladding and the jacket. The core is the innermost section and consists of fiber made of glass or plastic. The core has diameter in the range 8-100 micrometers. Each fiber is surrounded by its own cladding, which is a glass or plastic coating that has optical properties different from those of core. The interface between the core and the cladding acts as a reflector to confine light that would otherwise escape the core. The jacket is composed of plastic and other material layered to protect against moisture, abrasion, crushing and other environmental damage.

Optical fibers are widely used in communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication.

Most telephone company long-distance lines are now made of optical fiber.

UNIT-IINetwork Topologies

Short Answer Questions1. What is a Network?

1A. A computer network is a group of computer systems and other hardware devices that are linked together through communication channels to facilitate communication and resource-sharing among a wide range of users.

2. Write various advantages of networks.

2A. Networking of computers facilitates resource sharing, sharing of information, and, can be used as a communication medium, and also for backup and support.

3. List various disadvantage of Networks.3A.

1. Security must be maintained to avoid unauthorized access.2. There is a cause to affect viruses.3. Expensive because of hardware components hubs, cables, routers, NIC, etc., 4. If Server is down then the entire network is useless.

4. List various types of Networks.

4A.

-Local Area Networks (LAN)-Metropolitan Area Networks (MAN)-Wide Area Networks (WAN)-The Internet

5.Expand LAN, WAN, MAN.5A. LAN : Local Area Network

WAN: Wide Area NetworkMAN: Metropolitan Area Network

6.Expand BBN, GAN.6A. BBN: Back Bone Networks

GAN: Global Area Networks

7.What is Network Topology? List types of topologies?7A. Network topology defines how the computers, or nodes, within the network are physically arranged and connected to each other.

Types of topologies-Star Topology - Ring Topology- Line Topology- Bus Topology, - Tree Topology and Mesh Topology

8.Write any two advantages and two disadvantages of topologies?8A. Advantages:

1. We can choose the type of topology as per the requirement.2. All devices are connected to the transmission medium as backbone.

Disadvantages:1. Defective communication media cannot be identified easily.2. Expensive.

Long Answer Questions1. Explain different types of computer networks.1A. Different types of computer networks

Depending upon the geographical area covered by a network, it is classified as:– Local Area Network (LAN)– Metropolitan Area Network (MAN)– Wide Area Network (WAN)– Personal Area Network (PAN)

LAN(Local Area Network):A LAN is a network that is used for communicating among computer devices, usually within an office building or home.

Is limited in size, typically spanning a few hundred meters, and no more than a mile• Is fast, with speeds from 10 Mbps to 10 Gbps• Requires little wiring, typically a single cable connecting to each device• Has lower cost compared to MAN’s or WAN’s•

MAN(Metropolitan Area Network):

• A MAN is a large computer network that usually spans a city or a large campus.• A MAN is optimized for a larger geographical area than a LAN, ranging from several blocks of buildings to entire cities.• A MAN might be owned and operated by a single organization, but it usually will be used by many individuals and organizations. • A MAN often acts as a high speed network to allow sharing of regional resources.• A MAN typically covers an area of between 5 and 50 km diameter. • Examples of MAN: Telephone company network that provides a high speed DSL to customers and cable TV network.

WAN( Wide Area Network): • WAN covers a large geographic area such as country, continent or even whole of the world.• A WAN is two or more LANs connected together. To cover great distances, WANs may transmit data over leased high-speed phone lines or wireless links such as satellites. • Multiple LANs can be connected together using devices such as bridges, routers, or gateways, which enable them to share data.• The world's most popular WAN is the Internet.

PAN(Personal Area Network):

• A PAN is a network that is used for communicating among computers and computer devices (including telephones) in close proximity of around a few meters within a room• It can be used for communicating between the devices themselves, or for connecting to a larger network such as the internet.• PAN’s can be wired or wireless• A personal area network (PAN) is a computer network used for communication among computer devices, including telephones and personal digital assistants, in proximity to an individual's body.• The devices may or may not belong to the person in question. The reach of a PAN is typically a few meters.

2. With the help of diagrams, explain network topologies with their advantages and disadvantages.

2A. Some common network topologies include ring, bus, star, tree and mesh configurations. These topologies are defined below:

Diagram Kind of Topology Description, Advantages, and Disadvantages

Ring

Description:

Devices are connected from one to another to form a ring shape.

Each host is connected to the next and the last node is connected to the first.

A data token1 is used to grant permission for each computer to communicate.

Advantages:

Easy to install and wire. Because every computer is given equal access to the token,

no one computer can monopolize the network.

Disadvantages:

Requires more cable than a bus topology. If one computer fails it can affect the whole network. It is difficult to identify the problem if the entire network

shuts down.

Bus

Description:

All hosts are connected to the backbone cable in a linear2 fashion.

Advantages:

Easy to connect a computer or peripheral. Requires less cable length than a star topology.

Disadvantages:

If there is a break in the backbone cable, the entire network shuts down.

Both ends of the backbone cable require terminators. It is difficult to identify the problem if the entire network

shuts down.

Star

Description:

All hosts are connected to a single point of concentration. Usually uses a hub3 or switch4 as a center node. Range limits are about 100 meters from the hub Data on a star network passes through the hub or

concentrator before continuing to its destination.

Advantages:

It is easy to modify and add new computers to a star network without disturbing the rest of the network.

If one node or workstation (beside the middle node) goes down, the rest of the network will still be functional.

The center of a star network is a good place to figure out where the network faults are located.

You can use several cable types in the same network if the hub you have can handle multiple cable types.

Disadvantages:

Requires more cable than a bus topology. If the middle node goes down , then the entire network goes

down. It is more expensive than because all cables must be

connected to one central point.

Tree Description: One "root" node connects to other nodes, which in

turn connect to other nodes, forming a tree structure. Information

from the root node may have to pass through other nodes to reach

the end nodes.

Advantages:

• Point-to-point wiring for individual segments.

• Supported by several hardware and software vendors.

• All the computers have access to the larger and their immediate

networks.

Disadvantages:

• Overall length of each segment is limited by the type of cabling used.

• If the backbone line breaks, the entire segment goes down.

• More difficult to configure and wire than other topologies.

Mesh

Description:

Each host is connected to all the other hosts.

Advantages:

Increased reliability since there are multiple paths for each node to take.

Increased speed since shortcuts have been created by add more cables/links.

Disadvantages:

The cost of cabling all the hosts together is expensive and time consuming.

UNIT-IIILAN components and Communication Hardware

Short Answer Questions

1. What are LAN Components?1A. Server, client, hub, switch, repeater, router, NIC, Cables, Network operating system.

2. Write various types of LAN Components?2A. The various types of LAN components are

1. Network Devices such as Servers/clients etc.

2. Network Communication Devices hubs, routers, switches, repeater ,etc.

3. Network Interface Cards.

4. Cables.

5. Network Operating System. 3. Define: Server and Client

3A.

Server: A network server is a computer designed to process requests and deliver data to other (client) computers over a local network or the Internet.

Client: A client is a computer that accesses a service made available by a server. 

4. What is a file server?4A. File server – A file server is a computer attached to a network that has the primary purpose for sharing of files (such as documents, sound files, photographs, movies, images, databases, etc.) that can be accessed by the clients.

5. What are Ethernet Cards?5A. An Ethernet card is one kind of network adapter. These adapters support the Ethernet standard for high-speed network connections via cables. Ethernet cards are sometimes known as network interface cards (NICs).

6. What are Hubs and Switches?6A. Hub: A network hub acts as a centralized point for data transmission to computers in a LAN. When data from one computer reaches the hub it is broadcast to every computer in the network regardless of where the data is intended to go.

Switches: An alternative to the network hub is the network switch. Switches represent a newer networking technology that assigns each computer in the network a specific MAC address. This allows LANs using a network switch to route information to individual computers.

7. What is Router?7A. Routers: A Router is a device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP's network. Router reduces network traffic by using routing table.

8. What are Gateways?8A.Gateways: A gateway is a network element that acts as an entrance point to another network. For example an access gateway is a gateway between telephony network and other network such as internet. LANs may have component called gateways, which assists in transferring from one LAN to another LAN.

9. What is a Modem and list types of Modems?9A. MODEM (Modulator – DEModulator ): A modem is a device that enables a computer to transmit data over telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is in the form of analog waves. A modem converts the Digital signals into analog signals (Modulate) and converts the Analog signal into Digital signal(Demodulate).

Types of modems: -internal modem-external modem-Cable modem-DSL modem

10. Write briefly about ATM.10A. Asynchronous Transfer Mode (ATM) is a telecommunications concept defined by ANSI and ITU (formerly CCITT) standards for carriage of a complete range of user traffic, including voice, data, and video signals, and is designed to unify telecommunication and computer networks.

11. What is an adapter? What is the function of an Adapter?11A. An adapter (Network interface controller, network interface card) is a computer hardware component that connects a computer to a computer network.

Functions of an adapter:

The function of an adapter is to provide a physical link to a computer network. This connection allows computers to communicate with servers, as well as other computers on the network.

12. List types of Adapters.12A. 1. Traditional PCI adapters fit inside a desktop personal computer (often called a NIC). 2. A newer type of PCI adapter, "PC Card" adapters (sometimes called PCMCIA cards) insert into the side of a notebook computer. 3. A USB adapter plus into a standard USB port of any computer 4. A media adapter connects to the Ethernet port of an Xbox or Play station game console or other home entertainment product, providing a bridge to Wi-Fi wireless capability. 5. Newer notebook computers contain integrated wireless adapter chips.

13. What is a multiplexer? Write any two functions of it.13A. A communications device that multiplexes (combines) several signals for transmission over a single medium.

Functions of multiplexer:1. A multiplexer accepts multiple inputs and allows only one to go through as an output. 2. A multiplexer allows multiple users or applications to share a common physical medium by allocating

bandwidth appropriately.

14. Expand V-SAT, ATM, FTP, EDI.14A.

V-SAT: Very Small Aperture TerminalATM: Asynchronous Transfer Mode FTP: File Transfer ProtocolEDI: Electronic Data Interchange.

LONG ANSWER QUESTIONS

1. Explain briefly about any three LAN Components?

A.

Server: A network server is a computer designed to process requests and deliver data to other (client) computers over a local network or the Internet.

Client: A client is a computer that accesses a service made available by a server. 

Hubs: A network hub acts as a centralized point for data transmission to computers in a LAN. When data from one computer reaches the hub it is broadcast to every computer in the network regardless of where the data is intended to go.

2. Explain the function of a Modem with a neat diagram?2A.

MODEM(MOdulator–DEModulator ):  A modem is a device that enables a computer to transmit data over telephone or cable lines . Computer information is stored digitally, whereas information transmitted over telephone lines is in the form of analog waves. A modem converts the Digital signals into analog signals (Modulate) and converts the Analog signal into Digital signal(Demodulate). Modem is only device to connect our computer with internet. The following diagram explains how the connections are made.

Modems are mainly two types internal modems and external modems

Internal Modems: Internal modems are basically integrated on a chip. These are put up into the PCI slots of the computer. There is no need of any external power supply for internal modems. These modems use the power supply of the PC. Their installation in PC is quite very simple

External Modems: A serial cable connection is needed to connect an external modem to a PC. These modems use their own power supplies. These modems have their independent controls. External modems are many types as like Cable modem and DSL modem, etc.,

3. Discuss briefly about: Hubs and Switches.3A. Hub: A network hub acts as a centralized point for data transmission to computers in a LAN. When data from one computer reaches the hub it is broadcast to every computer in the network regardless of where the data is intended to go. Network bandwidth on LANs using a network hub is shared, which means that four computers on a hub will each get one-quarter the total bandwidth available on the hub.

Switches: An alternative to the network hub is the network switch. Switches represent a newer networking technology that assigns each computer in the network a specific MAC address. This allows LANs using a network switch to route information to individual computers. Because network switches do not broadcast to every computer on the network, they can simultaneously allot their full bandwidth to each computer.

4. Write about V-SAT and ATM.

4A. A very small aperture terminal (VSAT), is a two-way satellite ground station or a stabilized maritime V-SAT antenna with a dish antenna that is smaller than 3 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Data rates typically range from 56 kbit/s up to 4 Mbit/s. VSATs access satellite(s) in geosynchronous orbit to relay data from small remote earth stations (terminals) to other terminals (in mesh topology) or master earth station "hubs" (in star topology).

VSATs are most commonly used to transmit narrowband data (point of sale transactions such as credit card, polling or RFID data; or SCADA), or broadband data (for the provision of satellite Internet access to remote locations, VoIP or video). VSATs are also used for transportable, on-the-move (utilising phased array antennas) or mobile maritime communications.

ATM: Asynchronous Transfer Mode (ATM) is a telecommunications concept defined by ANSI and ITU (formerly CCITT) standards for carriage of a complete range of user traffic, including voice, data, and video signals, and is designed to unify telecommunication and computer networks. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells.

ATM provides data link layer services that run over a wide range of OSI physical Layer links. ATM has functional similarity with both circuit switched networking and small packet switched networking.

5. Discuss about a) Routers b) Gateways.

5A. Router: A Router is a device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP's network. Router reduces network traffic by using routing table.

Gateway: A gateway is a network element that acts as an entrance point to another network. For example an access gateway is a gateway between telephony network and other network such as internet. LANs may have component called gateways, which assists in transferring from one LAN to another LAN.

A gateway is generally a work station or server. It is a two-way path between networks. It is used to connect different types of networks. Gateway is a work station by which we can make our connection between external network and internal network. Gateway belongs to transport layer and application layer of the OSI model.

Gateways also connect the two networks even if the protocols are different. So protocol conversion is also done by gateways

UNIT-IVInternet Connectivity and Services

Short Answer Questions

1. What is an Internet?1A. An interconnected system of networks that connects computers around the world via the TCP/IP protocol.

2. Write advantages of Internet.2A. Internet provides E-Mail , information, online banking , chatting, buy or sell products Downloading softwares etc.,

3. What is a Browser? List types of browsers.3A. A browser is software that is used to access the internet.

Types of browsers are Google chrome, Mozilla Firefox, Internet explorer, Netscape navigator and opera etc.,

4. What is a Message?4A. A message is a string of bytes that is meaningful to the applications that use it. Messages are used to transfer information from one application program to another (or between different parts of the same application). The applications can be running on the same platform, or on different platforms.

5. What is an E-mail?5A. E-mail (Electronic Mail) is an electronic version of sending a letter. You can send e-mail from your computer at any time of the day to any address around the world and your electronic letter will arrive at its destination seconds after you send it, even if the receiver lives on the other side of the world.

6. Write any four uses of E-mail?6A. Uses of E-Mail are1. Fast - Messages can be sent anywhere around the world in an instant .2. Inexpensive - Transmission usually costs nothing, or at the most, very little .3. Simple - Easy to use, after initial setup.4. Efficient - Sending to a group can be done in one step .5. Versatile - Pictures, power-points or other files can be sent too.6. Printable – The hand copy is easy to obtain. We can correspond and save e-mail message and also we get electronic copy of message.

7. What is an attachment?7A. An attachment is simply an additional file sent with an email message. An attachment can be an image file, a Word document, or one of many other supported file types.

8. What is voice messaging?

8A. Voice message refers to a message that could be sent to a destination using voice media. Voice itself could be 'packaged' and sent through the IP backbone so that it reaches its marked 'address'.9. What is Internet Explorer?9A. Internet Explorer is a web browser and it was developed by Microsoft.

10. What is FTP?10A. File Transfer Protocol, or FTP, is a protocol used for transferring files from one computer to another - typically from your computer to a web server.

11. What is a Protocol and Write types of Network Protocols?11A. A network protocol defines rules and conventions for communication between network devices. Protocols for computer networking all generally use packet switching techniques to send and receive messages in the form of packets.

There are different types of network protocols are used for different purposes like FTP (File Transfer Protocol), HTTP (Hyper Text Transfer Protocol), TCP (Transmission Control Protocol), UDP (User Datagram Protocol) and IP (Internet Protocol).

12. What is Internet Security?12A. Internet security is a protection to the computer and files stored in it, from any harmful and malicious spyware through internet.. There are many antivirus software available to protect computers and files.

13. What is a virus?13A. A Virus is a piece of software that can infect other programs by modifying them; the modification includes a copy of the virus program, which can then go on to infect other programs.

14. What is a Trojan?14A. A Trojan is a malicious application that tricks as a authentic file or helpful program but whose real purpose is, for example, to grant a hacker unauthorized access to a computer. Trojan horses may steal information, or harm their host computer systems.

15. What is Hacking?15A. Hacking is an activity that is used by a hacker to steal the information from any of the device or computer system. Also a hacker can use the system to work as a server to route the information for the own purpose. Hackers can use the contact information of system and send spam emails to that email ids.

16. What is a Worm?16A. A Worm is a program that can replicate or infect itself and send copies from computer to computer across network connections. Upon arrival, the worm may be activated to replicate and propagate again. A worm actively seeks out more machines to infect and each machine that is infected serves as an automated launching pad for attacks on other machines.

17. Expand FTP, E-Mail, WWW, TCP/IP, ISDN, HTTP.17A.

FTP: File Transfer Protocol E-Mail: Electronic Mail WWW: World Wide Web TCP/IP: Transmission Control Protocol/Internet Protocol

ISDN: Integrated Services Digital NetworkHTTP: Hyper Text Transfer Protocol

Long Answer Questions

1. What is an Internet? Explain any three advantages and three disadvantages of Internet.

1A. Internet: An interconnected system of networks that connects computers around the world

via the TCP/IP protocol.

Advantages of Internet:

1. Email: E-mail is an online correspondence system. With e-mail you can send and receive instant electronic messages, which works like writing letters. Your messages are delivered instantly to people anywhere in the world, unlike traditional mail that takes a lot of time. Email is now an essential communication tools in business. It is also excellent for keeping in touch with family and friends. The advantages to email is that it is free ( no charge per use) when compared to telephone, fax and postal services.

2. Information: Any kind of information on any topic under the sun is available on the Internet. The ‘search engines’ on the Internet can help you to find data on any subject that you need. There is a huge amount of information available on the internet for just about every subject known to man, ranging from government law and services, trade fairs and conferences, market information, new ideas and technical support.

3. Services. Many services are now provided on the internet such as online banking, job seeking and applications, railway reservations , flight reservations and hotel reservations etc.,Disadvantages of Internet:

1. Personal Information: If you use the Internet, your personal information such as your name, address, etc. can be accessed by other people. If you use a credit card to shop online, then your credit card information can also be ‘stolen’ which is same as giving a blank check to someone.

2. Pornography: This is a very serious issue concerning the Internet, especially when it comes to young children. There are thousands of pornographic sites on the Internet which are harmful to the young children .

3. Spamming: This refers to sending unsolicited e-mails in bulk, which serve no purpose and unnecessarily clog up the entire system. Such illegal activities are frustrating for all Internet users, and so instead of just ignoring it, we should make an effort to try and stop these activities so that using the Internet can become that much safer.

2. Explain various Web Browsers.

2A.

Web Browsers:

1. Internet Explorer

It was developed by Microsoft in 1994 and released in 1995 as a supportive package to

Microsoft Windows line of operating systems. According to statistics, its usage share from 1999

to 2003-04 was around 95%. Microsoft occasionally releases updates for the previous versions of

IE, which have some enhanced capabilities. IE has come up a preview release of Internet Explorer

11.

Features: There are regular Microsoft updates that IE supports. Favicon allows an image to be

used as a bookmark. It supports Integrated Windows Authentication. It’s icon is as follows.

2. Mozilla Firefox

It is owned by Mozilla Corporation and was the result of an experimentation. 'Mozilla

Firefox' was officially announced in February 2004. It was earlier named Phoenix, Firebird, and

eventually Firefox. It is the second-most famous browser after Internet Explorer, as there were

around 100 million downloads within a year of its release. Until November 2008, 700 million

downloads were recorded.

Features: As it is an open source software, it allows everyone to access the code. It supports

tabbed browsing that allows the user to open multiple sites in a single window. Session storage is

also an important feature of Firefox, which allows the user to regain access to the open tabs after

he has closed the browser window. It’s icon is as follows.

3. Google Chrome

This web browser was developed by Google. Its beta and commercial versions were

released in September 2008 for Microsoft Windows.

Features: The main standout feature is the malware and phishing warning that the browser

suggests when the user wants to browse a site. Also, there is a user tracking option available with

Chrome. It’s icon is as follows.

3. Write various advantages and disadvantages of e-mail.

3A.

Advantages of E-mail

1. Fast - Messages can be sent anywhere around the world in an instant .

2. Inexpensive - Transmission usually costs nothing, or at the most, very little .

3. Simple - Easy to use, after initial setup.

4. Efficient - Sending to a group can be done in one step .

5. Versatile - Pictures, power-points or other files can be sent too.

6. Printable – The hand copy is easy to obtain. We can correspond and save e-mail message and

also we get electronic copy of message.

Disadvantages of E-mail

1. Emails may carry viruses. These are small programs that harm your computer system. They can read out your email address book and send themselves to a number of people around the world.

2. Many people send unwanted emails to others. These are called spam mails. It takes a lot of time to filter out the unwanted emails from those that are really important.

3. Emails cannot really be used for official business documents. They may be lost and you cannot sign them.

4. Your mailbox may get flooded with emails after a certain time so you have to empty it from time to time.

 

4. How do you send and receive an E-mail with an attachment.

4A. Sending an E-mail:

To Send an e-mail , sender must have email-id(user name and password), receiver’s email-id , message , subject of the mail and location of a file to be attached etc.,

1. You must open your email account provider such as gmail, yahoo or rediff etc., 2. Login into your email-id by using user name and password.3. After logged in , click on compose 4. Enter address of the receiver(s) in the "To" field 5. you must write the subject that means email is for what purpose in the “subject”field6. you must write in the contents of your email in message box.7. If you want to attach files , click on attach and give the location of a file to be attached.8. Finally , click on "Send" to send. If everything is correct , then you will be noticed that “your message has been sent, view message”

Receiving an E-mail :

To receive an e-mail , receive must have email-id (user name and password),

1. You must open your email account provider such as gmail, yahoo or rediff etc., 2. “Login” into your email-id by using user name and password.3. After logged in, click on inbox to see all the Emails you have received.4. After opening the Inbox you will see the person and the subject who have sent you the mail.5. Clicking on it will open the mail and you can see the data which have been sent to you.6. If an attachment is there, then you can view or download by clicking.7. There will be a reply option in case if you want to reply to the sender.8. you can save the message and attachments if you want.

5. Write about Internet Security.

5A.

Internet security is a protection to the computer and files stored in it , from any harmful and malicious spyware through internet.. There are many antivirus software available to protect computers and files.

Malicious software and antivirusMalicious software is software that is intentionally inserted in a system for

harmful purpose. There are different types of malicious programmes exist in the internet. Those are viruses, Trojan horse, worms, etc.,

Virus

A software program written to disrupt computer systems and to destroy data—viruses are the most well known Internet security threat.

Worms

Similar to viruses but much more dangerous. They spread rapidly by accessing your email address book and automatically forwarding themselves to every address it contains.

Trojan Horses

It is actually designed to cause loss or theft of computer data and to destroy computer systems. They usually arrive as email attachments or bundled with other software. Some give attackers unrestricted access to your computer anytime you’re online, allowing file transfers, adding or deleting of files and programs, and taking control of your mouse and keyboard.

Phishing:

A trick where Internet criminals send out false emails in the name of a legitimate organization in order to make victims into sending personal information back to be used in identity theft crimes.

Hacking: The persons making hawking are called Hackers. They are experts in computer and Internet skill levels sufficient enough to break security settings on personal computers and servers over the Internet. Some hackers do it for recreation, others for malicious intent.

Antivirus software

Antivirus software is a computer program that detects, prevents, and takes action to disarm or remove malicious software programs, such as viruses and worms.

To help prevent the most current viruses, you must update your antivirus software regularly. You can set up most types of antivirus software to update automatically.

UNIT-VHTML & Web Page Design

Short Answer Questions:

1. Define HTML.A. HTML stands for Hyper Text Markup Language and it is used to create web pages.

2. Write the syntax for Element in HTML.A.

1. An HTML element starts with a start tag / opening tag Syntax: <html> 2. An HTML element ends with an end tag / closing tag Syntax: </html>3. The element content is everything between the start and the end tag4. Some HTML elements have empty content5. Empty elements are closed in the start tag6. Most HTML elements can have attributes

3. What is the use of Paragraph tag?

A. Paragraph Tag (<p>) The <p> tag is responsible for arranging given data in a paragraph. <p> indicates the start of a paragraph. </p> indicates the end of a paragraph.

4. What are the attributes used in Font tag.A. There are three attributes used in font tag are size, color, and face to customize the fonts.

5. Write any three advantages of HTML.A.

1. First advantage it is widely used. 2. Every web browser supports HTML language. 3. Easy to learn and use. 4. It is by default in every windows so you don't need to purchase extra software.

6. Write different header tags available in HTML.A. There are six header tags H1 through H6. <h1> defines the largest heading. <h6> defines the smallest heading.

7. What is a hyperlink?A. A hyperlink is a word, phrase, or image that you can click on to jump to a new document or a

new section within the current document. These hyperlinks are mostly used in HTML.

8. Write different HTML tags.A. <html> - The main container for HTML pages

<head> - The container for page header information<title> - The title of the page<body> - The main body of the page

9. What is a frame?A. Frame is used to broken the browser window into multiple regions.

10. What are radio buttons?

A.

Radio buttons: Radio buttons are used when you want to let the visitor select one - and just one - option from a set of alternatives

11. What are check boxes?

A.

Check boxes: Check boxes are used when you want to let the visitor select one or more options from a set of alternatives

Long Answer Questions:

1. Write the structure of an HTML Program.

A. Structure of an HTML Program.

In every HTML program has a rigid structure. The entire web page is enclosed within <HTML> </HTML> tags. Within these tags two separate sections are created using the <HEAD> </HEAD> tags and the <BODY> </BODY> tags. These sections are described below.

1. < Head> tag

Information placed in this section is essential to the inner workings of the document and has nothing to do with the content of the document. With the exception of information contained within the <TITLE> </TITLE> tags, all information placed within the <HEAD> </HEAD> tags is not displayed in the browser. The HTML tags used to indicate the start and end of the head section are:

<HEAD>

<TITLE> </TITLE>

</HEAD>

The <TITLE> tag sets the title of the document which will be displayed in the title bar of the browser window.

2. < Body> tag

The tags used to indicate the start and end of the main body of textual information are:

<BODY>

</BODY>

Page defaults like background color, text color, font size, font weight and so on can be specified as attributes of the <BODY> tag. The attributes that the <BODY> tag takes are:

bgcolor, background, text, etc.,Example

<html>

<head>

<title>

First Page

</title>

</head>

<body>

This is My First Web Page

</body>

</html>

2. Write various advantages and disadvantages of HTML.

A. Advantages of HTML: 1. First advantage it is widely used.

2. Every browser supports HTML language. 3. Easy to learn and use. 4. It is by default in every windows so you don't need to purchase extra software.

Disadvantages of HTML: 1. It can create only static and plain pages so if we need dynamic pages then HTML is not useful. 2. Need to write a lot of code for making simple webpage. 3. Security features are not good in HTML. 4. If we need to write long code for making a webpage then it produces some complexity.

3. Explain different formatting tags available in HTML.

A. Formatting TagsFormatting tags are used to change the format of text displayed on a webpage , e.g.. to change

the text in bold, italic etc.,

The tags listed in the table below can be used to change the format of text. Remember to include the closing tags at the end of the formatted text.

Tag Function Output<b> bold text This is bold.<big> big text I am big<del> deleted text<em> emphasized text This is emphasized text<i> italic text This is italic<ins> inserted text inserted text<small> small text I am small<strong> strong text I am strong!<sub> Subscript Textsubscript

<sup> Superscript Textsuperscript

<u> underlined text This is underlined text

<strike> Element displayed with strike through

Strikethrough

4. Explain the purpose of Image tag and write the attributes used in image tag. Image Tag

The image tag is used to place an image on the web page. The tag contains the attributes like

src, width, height, align, alt, border, vspace and hspace.

The attribute src means source and tells the browser where the image file is. The attributes height and width specifies the size of the image.

The attribute align specifies the position of the image i.e., left, right, top, middle, bottom, absmiddle, absbottom, baseline, texttop.

The alt attribute provides alternative information for an image if a user for some reason cannot view it.

You can create space between the image and surrounding text by defining vspace(vertical spacing) and hspace(horizontal spacing).

The border attribute places a border around the image. Example:

<html> <head>

<title> Image Tag Example

</title> </head> <body> <img src=”f:\flower.JPEG” border="5" width="200" height="200" alt="Browser not supperted" hspace=”100” vspace=”100”> </body>

</html>

5. Explain <table> with an example.

Table Tag

The <table> tag defines an HTML table. An HTML table consists of the <table> element and one or more <tr>, <th>, and <td> elements. The <tr> element defines a table row, the <th> element defines a table header, and the <td> element defines a table cell. The attributes used in <table> tag are “align=left, center or right”, border and bgcolor. The attributes used in <tr> tag are “align=left, center or right”, colspan and rowspan. For example, <td colspan=2> will take up two columns and <td rowspan=2> will take up two rows.

Example:

<html><head><title> Tabel tag example</title></head><body> <table bgcolor=”#cc00bb” border=”5” align=”center”> <tr> <th>Sl.No.</th><th>Vegetables</th><th> Fruits</th></tr> <tr> <td> 1. </td><td>Brinjal</td><td>Orange</td></tr> <tr> <td> 2. </td><td>Potato</td><td>Apple</td></tr> </table>

</body></html>

The output of the above HTML program is as follows.

6. Define a list. Explain various types of lists used in HTML.A. LISTS:

Lists are used to list out items, subjects or menu in the form of a list. HTML gives you three different types of lists.

<ul> - An unordered list. This will list items using bullets <ol> - A ordered list. This will use different schemes of numbers to list your items <dl> - A definition list. This is arrange your items in the same way as they are arranged in

a dictionary.

HTML Unordered Lists:

This list is created by using <ul> tag. Each item in the list is marked with a bullet. The bullet itself comes in three styles: squares, discs, and circles. The default bullet displayed by most web browsers is the traditional full disc.

Example:

<html>

<body>

<center>

<h2>II YEAR CSE PAPERS</h2>

</center>

<ul>

<li>GFC</li>

<li>ENGLISH</li>

<li>OOPS&JAVA</li>

<li>RDBMS</li>

<li>DCCN</li>

</ul>

</body>

</html>

This will produce following result:

II YEAR CSE PAPERS

GFC ENGLISH OOPS&JAVA RDBMS DCCN

You can use type attribute to specify the type of bullet you like. By default its is a disc. Following are the possible way:

<ul type="square">

<ul type="disc">

<ul type="circle">

2. HTML Ordered Lists :

This list is created by using <ol> tag. Each item in the list is marked with a number. By default The numbering starts from one and is incremented by one.

example:

<html>

<body>

<center>

<h2>II YEAR CSE PAPERS</h2>

</center>

<ol>

<li>GFC</li>

<li>ENGLISH</li>

<li>OOPS&JAVA</li>

<li>RDBMS</li>

<li>DCCN</li>

</ol>

</body>

</html>

This will produce following result:

II YEAR CSE PAPERS

1. GFC2. ENGLISH3. OOPS&JAVA4. RDBMS5. DCCN

You can use type attribute to specify the type of numbers you like. By default its is a generic numbers. Following are the other possible way:

<ol type="I"> - Upper-Case Numerals.

<ol type="i"> - Lower-Case Numerals.

<ol type="a"> - Lower-Case Letters.

<ol type="A"> - Upper-Case Letters.

3. HTML Definition Lists :

Definition List makes use of following three tags.

<dl> - Defines the start of the list <dt> - A term <dd> - Term definition </dl> - Defines the end of the list

Example:

<html>

<body>

<dl>

<dt><b>LAN</b></dt>

<dd>LAN stands for Local Area Network</dd>

<dt><b>WAN</b></dt>

<dd>WAN stands for Wide Area Network</dd>

</dl>

</body>

</html> >

This will produce following result:

LAN

LAN stands for Local Area Network

WAN

WAN stands for Wide Area Network

7. How the frames can be created in HTML.A.

Frames are used to broken the browser window into multiple regions. Each frame can contain different HTML documents. The <frameset> tag is a container for frames and replaces the body tag and <frame> tag is used to place the contents into the frame.

The attributes used in the <frameset>tag are rows or cols. If the window is to be divided into horizontal stripes then the row attribute should be used. If the window is to be divided into vertical stripes then the cols attribute should be used.

For Example, if you want to divide the browser window into two rows then you must specify like <frameset rows=”30%,70%”>.

<frame> sets a single frame in the framed page. <frame> always goes inside a <frameset> element. The src attribute, which is required, indicates the URL of the page that goes in the frame. In most situations you should also use name to give the frame a name so that links can target the frame.

Example for creating a frame with two regions.

First, create a simple html file

<html>

<head>

<title>first window</title>

</head>

<body>

ravi

</body>

</html>

Create a new folder somewhere and save this as ravi.html

Run this ravi.html and you can see a name “ravi” on the entire screen.

Now make another HTML document.

<html>

<head>

<title>second window</title>

</head>

<body>

kiran

</body>

</html>

Save this as kiran.html and save it in the same folder where you saved ravi.html

Run this kiran.html and you can see a name “kiran” on the entire screen.

We should not use body tag in main frame . Suppose if we want to split the screen horizonally we can use <frameset rows = “50%50%”>

<html>

<head>

<title>My Frame</title>

</head>

<frameset rows="50%,50%">

<frame src="ravi.html">

<frame src="kiran.html">

</frameset>

</html>

Above html saved with a name frame.html in the same folder where you saved the previous two files.

When we run the frame.html the output is as follows i.e “ravi” in the first window and “kiran in the second window.

8. Explain the concept of Internal Linking.

A. Internal Linking

HTML has facility to include internal links by assigning a location name to any individual point in an HTML document. This location name can then be added to the page’s URL. For internal linking , the anchor tag is used.

<a name=”name”></a>

To refer to the location use

<a href=”#name”>text</a>

Example: <html>

<head>

<title> Internal Linking Example </title>

</head>

<body>

<p><a href="#heading1">Link to heading 1</a></p>

<p><a href="#heading2">Link to heading 2</a></p>

<br><br><br><br><br><br><br><br><br><br>

<br><br><br><br><br><br><br><br><br><br>

<br><br><br><br><br><br><br><br><br><br>

<h1 id="heading1">heading 1</h1>

<p>Text text text text</p>

<h1 id="heading2">heading 2</h1>

<p>Text text text text</p>

</body>

</html>

9. Explain the concept of External Linking.

External Linking:The most important capability of the HTML is the ability to create hyperlinks to

documents and thereby make the world wide web as a collection of linked documents. The links

are created using anchor <a></a> tag. This element requires an attribute to mark the location of the object to get linked. The address of the object is specified using href attribute. The href attribute of the tag tells the browser to get another html document on the web.

Example:

<html><head><title> External linking example</title></head><body><a href="http:\\www.yahoo.com">YAHOO</a><br><a href="http:\\www.google.com">GOOGLE</a>

</body></html>When we run the above html , we can be linked to either yahoo.com or google.com

websites.

10. Define form. Explain various form objects used in HTML.

Forms:

A form is simply an area that can contain form fields. Form fields are objects that allow the visitor to enter information - for example text boxes, drop-down menus or radio buttons. The Input Element

The most important form element is the <input> element. The <input> element is used to select user information. An <input> element can vary in many ways, depending on the type attribute. An <input> element can be of type text field, checkbox, password, radio button, submit button, and more.Text Fields

Text fields are one line areas that allow the user to input text.

Syntax: <input type="text" > <form> First name: <input type="text" name="firstname"><br></form>

How the HTML code above looks in a browser:

First name:

Radio Buttons

Radio buttons are used when you want to let the visitor select one - and just one - option from a set of alternatives.

Syntax:<input type="radio">

<form> <input type="radio" name="sex" value="male">Male<br>

<input type="radio" name="sex" value="female">Female</form>

How the HTML code above looks in a browser:

Male

Female

Checkboxes

Check boxes are used when you want to let the visitor select one or more options from a set of alternatives.

Syntax: <input type="checkbox”>

<form> <input type="checkbox" name="vehicle" value="Bike">I have a bike<br> <input type="checkbox" name="vehicle" value="Car">I have a car </form>

How the HTML code above looks in a browser:

I have a bike

I have a car

Submit Button

A submit button is used to send form data to a server. The data is sent to the page specified in the form's action attribute. The file defined in the action attribute usually does something with the received input.

Syntax: <input type="submit">

<form name="input" action="html_form_action.asp" method="get"> Username: <input type="text" name="user"> <input type="submit" value="Submit"></form>

How the HTML code above looks in a browser:

Username:

If you type some characters in the text field above, and click the "Submit" button, the browser will send your input to a page called "html_form_action.asp". The page will show you the received input.

Reset Button

Submit

When a visitor clicks a reset button, the entries are reset to the default values.

Syntax: <input type="reset">

<form > Username: <input type="text" name="user"> <input type="reset" value="Reset"></form>

How the HTML code above looks in a browser:

Username:

UNIT-VIDHTML

SHORT ANSWER QUESTIONS

1. Define DHTML. List out the components of DHTML.A. DHTML: Dynamic Hyper Text Markup Language (DHTML) is a combination of Web

development technologies used to create dynamically changing websites.Components of DHTML

a. HTMLb. CSSc. Scriptingd. DOM

2. Write any three differences between HTML and DHTML.

Differences between HTML and DHTML

HTML

1. HTML means Hyper Text Markup Language.2. It is referred as a static HTML and static in nature. 3. A plain page without any styles and Scripts called as HTML.

DHTML

1. DHTML means Dynamic Hyper Text Markup Language.2. It is referred as a dynamic HTML and dynamic in nature. 3. A page with HTML, CSS, DOM and Scripts called as DHTML.

Reset

3.Write the advantages and disadvantages of DHTML.

A. Advantages: Dynamic content, which allows the user to dynamically change Web page content Dynamic positioning of Web page elements. Dynamic style, which allows the user to change the Web page’s color, font, size or

content.

Disadvantages:

It can be difficult to develop and debug because of lack of Web browser and technological support.

DHTML scripts may not work correctly in various Web browsers. The Web page layout may not display correctly when it is developed to display in

different screen size combinations and in different browsers.

4. Define Event and Event Handling.A. Event: Clicking a button, moving the mouse pointer over part of the Web page, selecting

some text on the page — these actions are called events.Event handling : An event handler allows you to execute code when an event occurs.

5. Define DOM.A. The W3C defines the DOM as "a platform- and language-neutral interface that will allow

programs and scripts to dynamically access and update the content, structure, and style of documents. The document can be further processed and the results of that processing can be incorporated back into the presented stage."

6. What are the advantages of CSS.A. CSS stands for Cascading Style Sheets. It is a way to divide the content from the layout on

web pages.

7. What are the attributes of a Layer Tag.

A.

Layer attributes:Id The name of the layer, used to identify it in your scriptLeft The position of the layer in relationship to the x coordinatesTop The position of the layer in relationship to the y coordinatesWidth The width of the layer, in px or %Height The height of the layer, in px or %bgColor The background color of the layerbackground The background image of the layer

Src The external html document contained inside the layer

LONG ANSWER QUESTIONS

1. Explain about DOM in DHTML.A. Document Object Model(DOM) in DHTML:

The Document Object Model is a platform- and language-neutral interface that will allow programs and scripts to dynamically access and update the content, structure and style of documents.

The HTML DOM is the Document Object Model only for HTML The HTML DOM is language and platform independent The HTML DOM defines a standard set of objects for HTML, and a standard way to manipulate

and access HTML documents The HTML DOM is W3C(World Wide Web Consortium) standard

The HTML DOM views HTML documents as a tree structure of elements which can be embedded within other elements. All elements, their attributes and their containing text, can be accessed through the DOM tree. Their contents can be deleted or modified, and new elements can be created by the DOM. The elements, their attributes , and their text are all known as nodes.

A HTML DOM Example

This coding example shows how the background color of an HTML document can be changed to blue when a user click on it:

<html>

<head><script type="text/javascript">function ChangeColor(){document.body.bgColor="blue"}</script></head>

<body onclick="ChangeColor()">Click on this document!</body></html>

2. Write the differences between HTML and DHTML.A. Differences between HTML and DHTML

HTML

1. HTML means Hyper Text Markup Language.2. It is referred as a static HTML and static in nature. 3. A plain page without any styles and Scripts called as HTML. 4. HTML sites will be slow upon client-side technologies. 5. HTML is error free language.6. HTML is not interactive and will not respond to the user actions.

DHTML

1. DHTML means Dynamic Hyper Text Markup Language.2. It is referred as a dynamic HTML and dynamic in nature. 3. A page with HTML, CSS, DOM and Scripts called as DHTML. 4. DHTML sites will be fast enough upon client-side technologies.5. DHTML is not an error free language.6. DHTML gives the designers to create visually outstanding HTML documents that

directly interact with the user.

3. Write a program for event handling.A.

Program for event handling:

Suppose if we want to change the color of a text by using event handling. Whenever we click on the text enclosed within the header will be changed as red color. This is called as event handling.

Program:<html><head><title>

EVENT HANDLING</title></head><body>

<h1 onclick="style.color='red'">Click on this text</h1> </body></html>

4. Explain about Layer Tag.A. Layer Tag

The <layer> tag is used to position and animate (through scripting) elements in a page. A layer can be thought of as a separate document that resides on top of the main one, all existing within one window. This new tag is dynamic in that it can be positioned anywhere on a web page

(without relation to other content), moved around, its content inside updated on demand, and more.

The basic syntax of the <layer> tag is as <layer>Text inside layer</layer>

The tag is a content tag, which means you can add into it content (like ). The text inside the layer floats above other text, and overlaps them. Imagine a layer as a sheet of paper that resides on top of the rest of the page, and does not take up space within the flow of the document.

Layer attributesLayer attributesId The name of the layer, used to identify it in your scriptLeft The position of the layer in relationship to the x coordinatesTop The position of the layer in relationship to the y coordinatesWidth The width of the layer, in px or %Height The height of the layer, in px or %bgColor The background color of the layerbackground The background image of the layerSrc The external html document contained inside the layer

Program<html><head><title> Layer Example</title></head><body><layer> <layer left=2 top=2> <h1><font color=gray>LAYER1</font></h1> </layer> <layer left=0 top=0> <h1>LAYER2</h1> </layer></layer></body></html>Output of the above program is

5. Explain various mouse events in DHTML.A. Mouse EventsA change in the state of a mouse, such as a button being pressed or the mouse being moved is called Mouse Event.

onmousedown - Occurs where mouse button is pressed. onmousemove - Occurs where mouse points moves above an element. onmouseup - Occurs where mouse button is released. onmouseout - Occurs when mouse pointer moves out of an element onclick - Occurs on a mouse click ondblclick - Occurs on a mouse double click

6. Write advantages and disadvantages of CSS.

A. Introduction to CSSCSS stands for Cascading Style Sheets. It is a way to divide the content from the layout on web pages. A CSS (cascading style sheet) file allows you to separate your web sites HTML content from it’s style. As always you use your HTML file to arrange the content, but all of the presentation (fonts, colors, background, borders, text formatting, link effects & so on…) are accomplished within a CSS.

Advantages of CSS:

1. Define the look of your pages in one place rather than repeating yourself over and over again throughout your site.

2. Easily change the look of your pages even after they're created. Since the styles are defined in one place you can change the look of the entire site at once.

3. Define font sizes and similar attributes with the same accuracy as you have with a word processor - not being limited to just the seven different font sizes defined in HTML.

4. Position the content of your pages with pixel precision.

5. Redefine entire HTML tags. Say for example, if you wanted the bold tag to be red using a special font - this can be done easily with CSS.

6. Define customized styles for links - such as getting rid of the underline.

7. Define layers that can be positioned on top of each other (often used for menus that pop up).

The one disadvantage is:

1. These will only work on version 4 browsers or newer. However, more than 95% of all browsers live up to that.

7. Explain about CSS selector.

CSS SelectorsCSS Selectors are the names that you give to your different styles. In the style definition you define how each selector should work (font, color etc.).Then, in the body of your pages, you refer to these selectors to activate the styles.

Program<HTML><HEAD><style type="text/css"> b.headline {color:red; font-size:22px; font-family:arial; text-decoration:underline}</style></HEAD><BODY><b>This is normal bold</b><br><b class="headline">This is headline style bold</b></BODY></HTML>Output

8. Write about Inline Style Sheet.

A. Inline Style Sheet

Inline style sheets are used when you want to apply a style to a single occurrence of an element. Inline style sheets are declared within individual tags and affect those tags only. Inline style sheets are declared with the style attribute.

Program

<html> <head> </head> <body> <p style="color:red"> The text in this paragraph will be red</p> <p style="color:green"> The text in this paragraph will be green </p> </body> </html>The output of the above program is

9. Write about External Style Sheet.A. External Style Sheet

External stylesheet is used when you want to apply one style to many pages. If you make one change in an external stylesheet, the change is universal on all the pages where the stylesheet is used.

An external stylesheet is declared in an external file with a .css extension. It is called by pages whose interface it will affect. External stylesheets are called using the <link> tag which should be placed in the head section of an HTML document. This tag takes three attributes.

Attributes of the <link> tag:

•rel - When using an external stylesheet on a webpage, this attribute takes the value "stylesheet"

•type - When using an external stylesheet on a webpage, this attribute takes the value "text/css"

•href - Denotes the name and location of the external stylesheet to be used.

Note: In external style sheet, you have to create two files one is for specifying styles to the tags and other is the file where you want to apply the above styles. First program will be typed in a notepad and give an extension .html and the second program will be typed in notepad and give and extension .css and then run the html program you will get the output.

First Program named ess.html

<html>

<head><link rel="stylesheet" type="text/css" href="style1.css" /></head><body>

<p>The text in this paragraph will be blue.</p>

</body></html>

Second program named style1.css

p {color:blue}

When we run the ess.html , the output will be as follows

10.Write about Internal Style Sheet.A. Internal or Embedded Style Sheet:

Internal stylesheet is used when you want an HTML document to have a unique style. An internal stylesheet is defined using the <style> tag and goes in the head section of an HTML document.

The <style> tag specifies the content type of a stylesheet with its type attribute which should be set to "text/css". In internal style sheet once if you specify the style property to any tag then it will apply to all the tags defined with in the body section.

Syntax:<style type="text/css">

styles go here</style>

Program

<html> <head> <style type="text/css"> p { color: blue }

</style> </head> <body> <p> The text in this paragraph will be blue. </p> <p> This paragraph too. </p> </body> </html>

Output of the above program is

EXPANSIONS in DCCN

SDM: Space-Division Multiplexing

FDM: Frequency-Division Multiplexing

TDM: Time-Division Multiplexing

CDM: Code Division Multiplexing

bps: bits per second

UTP : Unshielded Twisted Pair

STP: Shielded Twisted Pair

LAN : Local Area Network

MAN: Metropolitan Area Network

WAN: Wide Area Network

PAN: Public Area Network

BBN: Back Bone Networks

GAN: Global Area Networks

MODEM: Modulator-DEModulator

NIC: Network Interface Card

VSAT: Very Small Aperture Terminal

ATM: Asynchronous Transfer Mode

FTP: File Transfer Protocol

EDI: Electronic Data Interchange

E-Mail: Electronic Mail

WWW: World Wide Web

TCP/IP : Transfer Control Protocol/Internet Protocol

ISDN: Integrated Services Digital Network

HTTP: Hyper Text Transfer Protocol

HTML: Hyper Text Markup Language

DHTML: Dynamic Hyper Text Markup Language

DOM:  Document Object Model

CSS: Cascading Style Sheets

ISS: Inline style sheets

ESS: External style sheet

Model paper-I

COMPUTER SCIENCE & ENGG- 2ND YEAR

PAPER-3: DATA COMMUNICATION AND COMPUTER NETWORKS [THEORY]

Time:- 3 Hrs Max. Marks:- 50

SECTION-A 10 x 2=20

Note:- 1. Answer ALL Questions:

2. Each Question carries 2 Marks.

1. Define Data Communication.

1A. Data communication is the transmission of electronic data over some media. The media may be cables, microwaves or fiber optics.

2. What is Computer Network?

2A. A computer network is a group of computer systems and other hardware devices that are linked together through communication channels to facilitate communication and resource-sharing among a wide range of users.

3. What is Network Topology?3A. Network topology defines how the computers, or nodes, within the network are physically arranged and connected to each other.

4. What is HUB? Write types in it.4A. Hub: A common connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.

HUBs are basically three types: 1. Passive HUB 2. Active HUB 3. Intelligent HUB

5. What is an Internet?5A. An interconnected system of networks that connects computers around the world via the TCP/IP protocol.

6. What is the function of MODEM?6A. Computer information is stored in digital form, whereas the information transmitted over telephone lines is in the form of analog waves. A modem converts analog signals into digital signals(modulation) and converts digital signals into analog signal (demodulation).

7. Expand terms HTML, DHTML and WWW.7A. HTML: Hyper Text Markup Language

DHTML: Dynamic Hyper Text Markup LanguageWWW: World Wide Web

8. What is Hyperlink?8A. A hyperlink is a word, phrase, or image that you can click on to jump to a new document or a new section within the current document. These hyperlinks are mostly used in HTML.

9. Mention any two mouse events.

9A. onclick - Occurs on a mouse click ondblclick - Occurs on a mouse double click

10. What is CSS?10A. CSS stands for Cascading Style Sheets. It is a way to divide the content from the layout on web pages.

SECTION - B 5 x 6 = 30Note:- 1. Answer ALL Questions:

2. Each Question carries 2 Marks.

11. Explain basic of modes of Data Transmissions

11A. Modes of Data Transmission:

There are three ways for transmitting data from one point to another

1. Simplex: 1. In simplex mode the communication can take place only in one direction. The receiver receives the signal from the transmitting device. This mode of flow of information is Unidirectional. Example: Radio, T.V., Pager transmission.

2. Half-duplex: In half-duplex mode the communication channel is used in both directions, but only in one direction at a time. Thus a half-duplex line can alternately send and receive data. Example is the wireless communication.

3. Full-duplex: In full duplex the communication channel is used in both directions at the same time. Use of full-duplex line improves the efficiency as the line turn-around time required in half-duplex arrangement is eliminated. Example of this mode of transmission is the telephone line.

12. Explain about LAN, WAN and MAN.

12A. LAN(Local Area Network):A LAN is a network that is used for communicating among computer devices, usually within an office building or home.

o Is limited in size, typically spanning a few hundred meters, and no more than a mileo Is fast, with speeds from 10 Mbps to 10 Gbpso Requires little wiring, typically a single cable connecting to each deviceo Has lower cost compared to MAN’s or WAN’s

MAN(Metropolitan Area Network):

A MAN is a large computer network that usually spans a city or a large campus. • A MAN is optimized for a larger geographical area than a LAN, ranging from several blocks of buildings to entire cities. • A MAN might be owned and operated by a single organization, but it usually will be used by many individuals and organizations. • A MAN often acts as a high speed network to allow sharing of regional resources. • A MAN typically covers an area of between 5 and 50 km diameter. • Examples of MAN: Telephone company network that provides a high speed DSL to customers and cable TV network.

WAN( Wide Area Network):

• WAN covers a large geographic area such as country, continent or even whole of the world. • A WAN is two or more LANs connected together. To cover great distances, WANs may transmit data over leased high-speed phone lines or wireless links such as satellites. • Multiple LANs can be connected together using devices such as bridges, routers, or gateways, which enable them to share data. • The world's most popular WAN is the Internet.

13. Explain Bus Topology in detail13A. Bus Topology:

Description:

All hosts are connected to the backbone cable in a linear fashion as shown below.

Advantages: Easy to connect a computer or peripheral. Requires less cable length than a star topology.

Disadvantages: If there is a break in the backbone cable, the entire network shuts down. Both ends of the backbone cable require terminators. It is difficult to identify the problem if the entire network shuts down.

14. Explain about ROUTER and Bridge

14A. Router: Routers are small physical devices that join multiple networks together. Technically, a router is a Layer 3 gateway device, meaning that it connects two or more networks and that the router operates at the network layer of the OSI model.

Bridges: I will write notes later

15. Explain about E-mail.

15A. E-mail is an electronic version of sending a letter. You can send e-mail from your computer at any time of the day to any address around the world and your electronic letter will arrive at its destination seconds after you send it, even if the receiver lives on the other side of the world.

E-mail addresses are different from normal mailing addresses. An e-mail address normally has four parts. The first part is the name of the user. The second part is the '@ 'sign. The third part comes after the @ sign and is the name of the service provider. The final part is the name of the domain (eg. .com, .net etc.).

Ex: chanukya999@gmail.com , sbrao1@yahoo.com .

Advantages of E-Mails:

1. Fast - Messages can be sent anywhere around the world in an instant .

2. Inexpensive - Transmission usually costs nothing, or at the most, very little .

3. Simple - Easy to use, after initial setup.

4. Efficient - Sending to a group can be done in one step .

5. Versatile - Pictures, power-points or other files can be sent too.

6. Printable – The hand copy is easy to obtain. We can correspond and save e-mail

message and

also we can get electronic copy of message.

Disadvantages of E-mail

1. Emails may carry viruses. These are small programs that harm your computer system. They can read out your email address book and send themselves to a number of people around the world.

2. Many people send unwanted emails to others. These are called spam mails. It takes a lot of time to filter out the unwanted emails from those that are really important.

3. Emails cannot really be used for official business documents. They may be lost and you cannot sign them.

4. Your mailbox may get flooded with emails after a certain time so you have to empty it from time to time.

5.

16. Explain the following tags with an example –FONT,IMG

16A. Font Tags : The tag is used for text Styling. The Tag contains various attributes like face, color and size. The color attribute indicates the color of the text, size attribute indicates the size of the text being formatted. If you want to change the size of the text larger then set size=”+x”. If you want to change the size of the text smaller then set size=”-x”, where x represents the number of font point sizes. The attribute face refers to the type of font.

Example:

<html>

<head>

<title>

Font Tag Example

</title>

</head><body><font color="red" size="+10" face="Algerian">The printed text is in red color, 10 point size and also Algerian style font. </font>

</body>

</html>

Output:

Image Tag

The image tag is used to place an image on the web page. The tag contains the attributes like src, width, height, align, alt, border, vspace and hspace.

The attribute src means source and tells the browser where the image file is. The attributes height and width specifies the size of the image. The attribute align specifies the position of the image i.e., left, right, top,

middle, bottom, absmiddle, absbottom, baseline, texttop. The alt attribute provides alternative information for an image if a user for

some reason cannot view it. You can create space between the image and surrounding text by defining

vspace(vertical spacing) and hspace(horizontal spacing). The border attribute places a border around the image.

Example:

<html>

<head>

<title>

Image Tag Example

</title>

</head><body> <img src=”f:\flower.JPEG” border="5" width="200" height="200" alt="Browser not supperted" hspace=”100” vspace=”100”>

</body>

</html>

Output:

17. Describe attributes of BODY Tag17A. Body Tag:The tags used to indicate the start and end of the main body of textual information are:

<BODY>

</BODY>

Page defaults like background color, text color, font size, font weight and so on can be specified as attributes of the <BODY> tag. The attributes that the <BODY> tag takes are:

BGCOLOR: Changes the default background color to whatever color is specified with this tag. The user can specify a color by name or its equivalent hexadecimal number.

For example, <body bgcolor=”#FF0000″ text=”#FFFFFF”>

BACKGROUND: Specifies the name of the gif/png/jpg file that will be used as the background of the document. This gif/png/jpg tiles up across the page to give a background.

For example, <body background=”winter.jpg” text=”#FFFFFF”>

TEXT: Changes the body text color from its default value to the color specified with this attribute.

Note: “winter.jpg” is an image which should be placed in your system.

Example:

<html>

<head>

<title>

First Page

</title>

</head><body> This is My First Web Page

</body>

</html>

OUTPUT:

18. Explain advantages of DHTML

DHTML is a way for you to change the way your pages look. You can instantly change the color of a page with the click of the mouse or without the click of a mouse. You can cause things to happen just by moving the mouse around the page. You can also create a slideshow for your site, create an announcement page that moves on to your real site by itself, and make your pages do strange things while loading and more.

Dynamic Hyper Text Markup Language (DHTML) is a combination of Web development technologies used to create dynamically changing websites. Web pages may include animation, dynamic menus and text effects. The technologies used include a combination of HTML, JavaScript or VB Script, CSS and the document object model (DOM).

Advantages:

Dynamic content, which allows the user to dynamically change Web page content Dynamic positioning of Web page elements. Dynamic style, which allows the user to change the Web page’s color, font, size or content.

Model paper-IICOMPUTER SCIENCE & ENGG- 2ND YEAR

PAPER-3: DATA COMMUNICATION AND COMPUTER NETWORKS [THEORY]Time:- 3 Hrs Max. Marks:- 50

SECTION-A 10 x 2=20Note:- 1. Answer ALL Questions:

2. Each Question carries 2 Marks.

1. Define Bandwidth.

1A. Bandwidth means the amount of data that can be transferred from one point to another in a given time period (usually a second). Bandwidth is usually expressed in bits per second (bps).

2. What is a Computer Network?2A. . A computer network is a group of computer systems and other hardware devices that are linked together through communication channels to facilitate communication and resource-sharing among a wide range of users.

3. What are various types of Networks.3A. Various types of networks are

LAN, MAN,WAN,PAN etc.,

4. Expand V-SAT, ATM, FTP, EDI.

4A. V-SAT: Very Small Aperture Terminal

ATM: Asynchronous Transfer Mode

FTP: File Transfer Protocol

EDI: Electronic Data Interchange

5. What is an Internet?5A. An interconnected system of networks that connects computers around the world via the TCP/IP protocol.

6. What is a virus?6A. A Virus is a piece of software that can infect other programs by modifying them; the modification includes a copy of the virus program, which can then go on to infect other programs.

7. Define HTML.7A. "HTML" means "HyperText Markup Language". HTML is used to create web pages.

8. What are frames?8A. Framed Layout is used to broken the browser window into multiple regions are called frames.

9. List out the components of DHTML.9A. DHTML requires four independent components to work. They are HTML, Cascading Style Sheets, Scripting and the Document Object Model.

10. Define DOM.10A. DOM stands for Document Object Model . It is the specification for how objects in a webpage (text, images, headers, links, etc.) are represented.

SECTION - B 5 x 6 = 30Note:- 1. Answer ALL Questions:

2. Each Question carries 2 Marks.

11. Explain basic of modes of Data Transmissions.

11A. Types of Transmission Modes

There are three ways for transmitting data from one point to another

1. Simplex: 1. In simplex mode the communication can take place only in one direction. The receiver receives the signal from the transmitting device. This mode of flow of information is Unidirectional. Example: Radio, T.V., Pager transmission.

2. Half-duplex: In half-duplex mode the communication channel is used in both directions, but only in one direction at a time. Thus a half-duplex line can alternately send and receive data. Example is the wireless communication.

3. Full-duplex: In full duplex the communication channel is used in both directions at the same time. Use of full-duplex line improves the efficiency as the line turn-around time required in

half-duplex arrangement is eliminated. Example of this mode of transmission is the telephone line.

12. Explain the advantages of Networks.

12A. ADVANTAGES OF COMPUTER NETWORKS Following are some important advantages of computer networks:

1. Data and Information Sharing:Different employees of an organization can share common information with the help of

computer network.

2. Software Sharing:Different software can be shared with the help of computer networks.

3. Hardware SharingWe can share hardware devices like Printers , hard disks, CD-Rom Drives / Writers, modems,

routers and scanners etc.

4. Money Saving:We can save a lot of money by using computer networking, because of sharing the same software

and hardware in a network.

5. Internet Sharing:We can buy only one DSL internet connection and share it with in whole organization with the

help of computer networking.

6. Easy Communication Within OrganizationWe can send and receive messages and files in the organization from one computer to another

through network.

13. Explain the Topology of Networks with advantages and disadvantages.

13A. Some common network topologies include ring, bus, star, tree and mesh configurations.

These topologies are defined below:

Diagram Kind of Topology Description, Advantages, and Disadvantages

Ring

Description:

Devices are connected from one to another to form a ring shape. Each host is connected to the next and the last node is connected

to the first. A data token1 is used to grant permission for each computer to

communicate.

Advantages:

Easy to install and wire. Because every computer is given equal access to the token, no

one computer can monopolize the network.

Disadvantages:

Requires more cable than a bus topology. If one computer fails it can affect the whole network. It is difficult to identify the problem if the entire network shuts

down.

Bus

Description:

All hosts are connected to the backbone cable in a linear2 fashion.

Advantages:

Easy to connect a computer or peripheral. Requires less cable length than a star topology.

Disadvantages:

If there is a break in the backbone cable, the entire network shuts down.

Both ends of the backbone cable require terminators. It is difficult to identify the problem if the entire network shuts

down.

Star Description:

All hosts are connected to a single point of concentration. Usually uses a hub3 or switch4 as a center node. Range limits are about 100 meters from the hub Data on a star network passes through the hub or concentrator

before continuing to its destination.

Advantages:

It is easy to modify and add new computers to a star network without disturbing the rest of the network.

If one node or workstation (beside the middle node) goes down, the rest of the network will still be functional.

The center of a star network is a good place to figure out where the network faults are located.

You can use several cable types in the same network if the hub you have can handle multiple cable types.

Disadvantages:

Requires more cable than a bus topology. If the middle node goes down , then the entire network goes

down. It is more expensive than because all cables must be connected to

one central point.

Tree

Description: One "root" node connects to other nodes, which in turn connect to other nodes, forming a tree structure. Information from the root node may have to pass through other nodes to reach the end nodes.

Advantages:

• Point-to-point wiring for individual segments.

• Supported by several hardware and software vendors.

• All the computers have access to the larger and their immediate

networks.

Disadvantages:

• Overall length of each segment is limited by the type of cabling used.

• If the backbone line breaks, the entire segment goes down.

• More difficult to configure and wire than other topologies.Mesh Description:

Each host is connected to all the other hosts.

Advantages:

Increased reliability since there are multiple paths for each node to take.

Increased speed since shortcuts have been created by add more cables/links.

Disadvantages:

The cost of cabling all the hosts together is expensive and time consuming.

14.Explain briefly about LAN Components.

A.

LAN Components:

6. Network Devices such as Servers/clients etc.

7. Network Communication Devices hubs, routers, switches, repeater ,etc.

8. Network Interface Cards.

9. Cables.

10. Network Operating System.

Server: A network server is a computer designed to process requests and deliver data to other

(client) computers over a local network or the Internet.

Client: A client is a computer that accesses a service made available by a server. 

Hubs: A network hub acts as a centralized point for data transmission to computers in a LAN.

When data from one computer reaches the hub it is broadcast to every computer in the network

regardless of where the data is intended to go. Network bandwidth on LANs using a network

hub is shared, which means that four computers on a hub will each get one-quarter the total

bandwidth available on the hub.

Switches: An alternative to the network hub is the network switch. Switches represent a newer

networking technology that assigns each computer in the network a specific MAC address. This

allows LANs using a network switch to route information to individual computers. Because

network switches do not broadcast to every computer on the network, they can simultaneously

allot their full bandwidth to each computer.

Router:  A Router is a device that forwards data packets along networks. A router is connected to

at least two networks, commonly two LANs or WANs or a LAN and its ISP's network. Router

reduces network traffic by using routing table.

Repeater: A network device used to regenerate or replicate a signal. Repeaters are used in

transmission systems to regenerate analog or digital signals distorted by transmission loss. Analog

repeaters frequently can only amplify the signal while digital repeaters can reconstruct a signal to

near its original quality.

Network Interface Card: Network interface cards, commonly referred to as NICs, and are used

to connect a PC to a network. The NIC provides a physical connection between the networking

cable and the computer's internal bus.

Cables: Cables connect computer components and devices, allowing them to communicate with

each other.

Network Operating System(NOS): An operating system that includes special functions for

connecting computers and devices into a local area network. Network Operating system

software, such as Microsoft Windows NT or 2000, Novell NetWare, Unix and Linux.

15. How do you send and receive an E-mail with an attachment .

15A. Sending an E-mail:

To Send an e-mail , sender must have email-id(user name and password), receiver’s email-id , message , subject of the mail and location of a file to be attached etc.,

1. You must open your email account provider such as gmail, yahoo or rediff etc., 2. Login into your email-id by using user name and password.3. After logged in , click on compose 4. Enter address of the receiver(s) in the "To" field 5. you must write the subject that means email is for what purpose in the “subject”field6. you must write in the contents of your email in message box.7. If you want to attach files , click on attach and give the location of a file to be attached.8. Finally , click on "Send" to send. If every thing is correct , then you will be noticed that “your message has been sent, view message”

Receiving an E-mail :

To receive an e-mail , receive must have email-id(user name and password),

1. You must open your email account provider such as gmail, yahoo or rediff etc., 2. Login into your email-id by using user name and password.3. After logged in , click on inbox to see all the Emails you have received.

4. After opening the Inbox you will see the person and the subject who have sent you the mail.5. Clicking on it will open the mail and you can see the data which have been sent to you.6. If an attachment is there ,then you can view or download by clicking.7. There will be a reply option in case if you want to reply to the sender.

8. you can save the message and attachments if you want.

16. Write the advantages and disadvantages of HTML.

16A.

Advantages of HTML: 1. First advantage it is widely used. 2. Every browser supports HTML language. 3. Easy to learn and use. 4. It is by default in every windows so you don't need to purchase extra software.

Disadvantages of HTML: 1. It can create only static and plain pages so if we need dynamic pages then HTML is not useful. 2. Need to write a lot of code for making simple webpage. 3. Security features are not good in HTML. 4. If we need to write long code for making a webpage then it produces some complexity.

17. Write about creation of frames.

17A.

Creation of Frames

Framed Layout is used to broken the browser window into multiple regions called frames. Each frame can contain different HTML documents. The <frameset> tag is a container for frames and replaces the body tag and <frame> tag is used to place the contents into the frame.

The attributes used in the <frameset>tag are rows or cols. If the window is to be divided into horizontal stripes then the row attribute should be used. If the window is to be divided into vertical stripes then the cols attribute should be used.

For Example, if you want to divide the browser window into two rows then you must specify like <frameset rows=”30%,70%”>.

<frame> sets a single frame in the framed page. <frame> always goes inside a <frameset> element. The src attribute, which is required, indicates the URL of the page that goes in the frame. In most situations you should also use name to give the frame a name so that links can target the frame.

Example:

<html>

<head>

<title>Frames Examples</title>

<frameset rows=”40%,*”>

<frame src=”frame1.html”>

<frame src=”frame2.html>

</frameset>

</head>

</html>

frame1.html

<html>

<head>

<title> frame1</title>

</head>

<body>

<marquee><h1>COMPUTER SCIENCE & ENGINEERING</h1></marquee>

</body>

</html>

frame2.html

<html><head><title>frame2</title>

</head>

<body>

<marquee><h1>COMPUTER SCIENCE & ENGINEERING</h1></marquee>

</body></html>

Output:

18. Explain various mouse events in DHTML

Mouse Events

A change in the state of a mouse, such as a button being pressed or the mouse being moved is called Mouse Event.

onmousedown - Occurs where mouse button is pressed. onmousemove - Occurs where mouse points moves above an element. onmouseup - Occurs where mouse button is released. onmouseout - Occurs when mouse pointer moves out of an element onclick - Occurs on a mouse click ondblclick - Occurs on a mouse double click

Example program for MouseDown and MouseUp event.

<html>

<head>

<title>

Mouse UP and DOWN events

</title>

</head>

<body>

<h1 id="text"onMouseup="text.style.color='red'" onMousedown="text.style.color='blue'">when mouse pressed it will in blue color and when mouse released it will in red color</h1>

</body>

</html>

Output: