Section 9.1 Explain the structure of the Internet Define the role of regional networks Explain what...

Section 9.1• Explain the structure of the Internet• Define the role of regional networks• Explain what an ISP does

Section 9.2• Explain the Domain Name System• Demonstrate how the DNS database system functions• Identify the role of ICANN

Section 9.3• Explain how IP addressing is used• Define the five classes of IP addresses• Demonstrate how to use subnet masks

Section 9.4• Explain the function of a Web browser• Describe different ways of searching for information• Identify several ways the Web is used as entertainment

pp. 252-2549.1

Main Ideas

The Internet is a collection of smaller networks. Regional networks are connected by high-speed communications lines called the backbone. Internet Service Providers provide access to the regional networks to home and business users.

Key Terms

backbone

regional network

Network Access Point (NAP)

Internet Service Provider (ISP)

Guide to Reading

Structure of the Internet

pp. 252-2549.1

The Internet is an internetwork. The foundation of the Internet is a backbone of high-speed communications lines that interconnect many regional networks.

backbone A high speed communications path that interconnects many regional networks. (p. 252)

The Backbone


pp. 252-2549.1

The Backbone

The Internet is the largest network of networks.


pp. 252-2549.1

Regional networks connect to a national backbone through one of many major locations known as Network Access Points (NAPs).

Most NAPs are created and maintained by major telecommunications companies, such as MCI and AT&T.

regional network A collection of small networks. For example, there are regional networks that serve the Northeast, Midwest, West, East, Southeast, Northwest, and Central California. (p. 253)

Network Access Point (NAP) The major location at which regional networks connect to a national backbone to join the larger Internet. (p. 253)

Regional and Other Networks


pp. 252-2549.1

To connect to the Internet, an Internet Service Provider (ISP) is needed.

An ISP is an agent that provides a pipeline to the Internet.

Internet Service Provider (ISP) An online service provider. (p. 253)

Internet Service Providers


pp. 256-2619.2

Main Ideas

Internet sites are categorized into domains according to organization type or geographic location. Domain names are resolved to IP addresses by DNS servers. ICANN is the organization responsible for assigning IP addresses.

Key Terms

DNS name server

root server

cache

Internet Corporation for Assigned Names and Numbers (ICANN)

Guide to Reading

Internet and Web Communities

pp. 256-2619.2

Domains

In addition to its physical structure and organization, the Internet is built upon the concept of domains.

The Internet classification is called the Domain Name System (DNS). DNS is used to uniquely identify sites based on a treelike hierarchy. This hierarchy includes a top-level domain, a second-level domain, and, often, one or more subdomains.


pp. 256-2619.2

Domains

Top-level domains organize sites by geography or organization type.


pp. 256-2619.2

DNS also refers to databases distributed among a number of DNS name servers.

In reality, apple.com is just an easy name to remember.

On the Internet, sites are identified by an Internet Protocol (IP) address. An IP address is a 32-bit number. It is divided into four 8-bit groups that look like the following: 192.168.1.100

DNS name servers A server that holds and looks through its DNS database to match domain names to IP addresses, then resolves the IP address. (p. 258)

DNS Databases and IP Addresses


pp. 256-2619.2

The root servers (or servers) responsible for sites within the .com domain contain the information needed to locate the server for apple.com. That is all it does. The root server does not concern itself with any lower levels—subdomains—within apple.com.

root server A DNS server that is responsible for tracking top-level domain names (.com, .org, .net, and so on). (p. 259)



pp. 256-2619.2


Requests are passed up the chain of DNS servers until an address is resolved or is not found.


pp. 256-2619.2

The responsibility for registering domain names is handled by a the Internet Corporation for Assigned Names and Numbers (ICANN).

Internet Corporation for Assigned Names and Numbers (ICANN) A nonprofit organization that registers domain names, preserves the operational stability of the Internet, and oversees the Internet’s root server system. (p. 261)

ICANN


pp. 256-2619.2

You Try It

• Activity 9A – Finding Domain Registration Information

(p. 258)• Activity 9B – Displaying the DNS Cache (p. 260)


pp. 262-2679.3

Main Ideas

IP addresses are used to uniquely identify computers on the network. Subnet masks are used in conjunction with IP addresses to identify the network ID and the host ID. Network functions aid in working with IP addresses.

Key Terms

address spaceloopback addresssubnet maskInternet Protocol version 6 (IPv6)Address Resolution Protocol (ARP)Reverse Address Resolution Protocol (RARP)Dynamic Host Configuration Protocol (DHCP)Windows Internet Naming Service (WINS)

Guide to Reading

Internet Connections & Addressing

pp. 262-2679.3

IP Addressing

When a domain is registered, an IP address, or block of IP addresses, is assigned to that domain.

This address identifies two things:

• the network • a host (computer) on that network

A system of IP address classes is used to keep one network separate from other networks.


pp. 262-2679.3

A range of assignable IP addresses is called the address space. However, not all these addresses are available for assignment, as some are reserved for special use.

The address 127.0.0.1 is a special reserved address, called a loopback address.

address space A range of assignable IP addresses technically runs from 0.0.0.0 to 255.255.255.255. (p. 263)

loopback address A special reserved IP address used to test whether a computer’s network capabilities are functioning. (p. 263)

IP Addressing


pp. 262-2679.3

IP Addressing

The assignable address space is divided into five classes and is identified by the binary form of the IP address.


pp. 262-2679.3

For an IP address to be valid, it must use a combination of an IP address, along with a subnet mask.

You can use an easy formula to calculate the number of subnets a given number of subnet bits will create.

2n = number of subnetworks

The n represents the number of bits used as the subnet ID.

subnet mask A mask used in conjunction with IP addresses to determine the portion of the IP address that identifies the network and the portion that identifies the host. Identifies the first 24 bits as the network address, with the remaining 8 bits identifying the host. (p. 263)

IP Addressing


pp. 262-2679.3

Internet Protocol version 6 (IPv6) is the latest generation of the IP protocol.

IPv6 uses 128-bit addresses, which works out to 4 billion times 4 billion times 4 billion times the current number (4 billion) of IP addresses.

Internet Protocol version 6 (IPv6) The latest generation of the IP protocol; also called Next Generation IP, or Ipng. (p. 265)

IP Addressing


pp. 262-2679.3

Many important services are involved for IP packets to get transmitted between Internet-networked computers.

• Address Resolution Protocol (ARP)

• Reverse Address Resolution Protocol (RARP)

Address Resolution Protocol (ARP) A protocol used to determine the hardware address (MAC address) that corresponds to an IP address. (p. 265)

Reverse Address Resolution Protocol (RARP) A protocol used to look up the IP address when the hardware, or MAC address, is known. (p. 265)

Working With TCP/IP Addresses


pp. 262-2679.3

• Dynamic Host Configuration Protocol (DHCP)

• Windows Internet Naming Service (WINS)

• Gateways

Dynamic Host Configuration Protocol (DHCP) A protocol used to automatically assign IP addresses within a network. (p. 266)

Windows Internet Naming Service (WINS) A service used to match computer names to IP addresses in a Windows network. (p. 266)

Working With TCP/IP Addresses


pp. 262-2679.3

You Try It

• Activity 9C – Configuring DHCP, WINS, and Gateway

(pg. 266)


pp. 269-2749.4

Main Ideas

Web browsers display pages written in HTML format. Search engines index and categorize sites on the Web to make information easy to find. Services like FTP, NNTP, and Telnet add capabilities such as file transfer and remote control of computers. The Web provides a variety of entertainment options.

Key Terms

Hypertext Markup Language (HTML)

search engine

Network News Transfer Protocol (NNTP)

newsgroups

Usenet

Telnet

online gaming

multiuser dungeon (MUD)

instant messaging (IM)

Guide to Reading

Internet and Web Services

pp. 269-2749.4

A Web browser is a software application that is used to view Internet documents written in Hypertext Markup Language (HTML).

Popular browser software includes Microsoft Internet Explorer and Apple’s Safari. Other popular browsers can be downloaded for free, including Netscape Navigator, Opera, and Mozilla.

Hypertext Markup Language (HTML) The language used to define the structure and layout of a Web page. HTML acts as a set of instructions that tells browser’s software how and where to place the page’s content. (p. 269)

Web Browser


pp. 269-2749.4

A search engine uses a spider, or robot, to “crawl” the Web on a regular basis. As it does this, it creates an index of every page it can find. Based on a complex set of criteria, pages can be ranked.

search engine A sight that uses automated software to index the Web. (p. 271)

Search Engines and Services


pp. 269-2749.4

FTP

Although search engines and the Web make finding information a snap, there are also other ways to find and retrieve information. One of the most widely used is the File Transfer Protocol (FTP).

FTP functionality is built into today’s Web browsers, making other software largely unnecessary. All you have to do is point your browser to an FTP site, log on, and start copying files.


pp. 269-2749.4

E-mail

One of the most popular uses of the Internet is e-mail. This global message service enables families, friends, business associates, and even complete strangers to communicate with one another. E-mail addresses are used to identify the “mailbox” of the person.


pp. 269-2749.4

News on the Internet has two different meanings.

1. News broadcasts

2. News is handled on the Internet by services based on the Network News Transfer Protocol (NNTP).

NNTP is a protocol that is used to distribute collections of articles called newsfeeds to a bewildering array of Interest-based newsgroups.

Network News Transfer Protocol (NNTP) A standard that is used to distribute collections of articles called newsfeeds. (p. 273)

newsgroup A group of individuals on the Internet with a common interest in a particular subject or set of related subjects. Newsgroups receive and post articles and discussions. (p. 273)

News


pp. 269-2749.4

Usenet is one of the most well-known news services that implements NNTP. When more than one user responds to a message, the original topic is called a thread.

Usenet An electronic bulletin board where users can post messages 24 hours a day, 365 days a year. (p. 273)

News


pp. 269-2749.4

Telnet is like remote control for computers. As long as the connecting computer has terminal emulation capabilities, it can use the resources and programs installed on the remote machine.

Telnet A TCP/IP protocol that runs on the Application Layer and allows a computer to log on to a remote computer and pretend it is attached directly to the host.(p. 273)

Telnet


pp. 269-2749.4

And, finally, what about some of the really fun things people get involved in on the Internet?

• Online gamingOnline gaming• Multiuser dungeons Multiuser dungeons (MUDs)(MUDs)• Chats• Instant messagingInstant messaging

online gaming Games available on the Internet that pit players from around the world against one another in real-time. (p. 274)

multiuser dungeon (MUD) A type of game available on the Internet that is an outgrowth of the popular dungeons and dragons type of interactive, multiplayer role playing games (RPGs). (p. 274)

instant messaging (IM) A type of e-mail process service that enables two (or more) people to establish a private communications channel, similar to calling someone on the phone. (p. 274)

Online Gaming, MUDs, Chats, andInstant Messaging


pp. 269-2749.4

You Try It

• Activity 9D – Searching By Category (p. 270)• Activity 9E – Narrowing a Web Search (p. 271)


Resources

For more resources on this chapter, go to the Introduction to Networks and Networking Web site at http://networking.glencoe.com.

Chapter 9

Section 9.1 Explain the structure of the Internet Define the role of regional networks Explain what...

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