SEMESTER 1 Chapter 3Application Layer Functionality and Protocols V 4.0

3.1.1.1 What does the application layer provide?

the interface between the applications we use to communicate and the underlying network over which our messages are transmitted

What are application layer protocols used for?

to exchange data between programs running on the source and destination hosts

3.1.1.2 What are the three primary functions of the Presentation Layer?

Coding and conversion of Application layer data to ensure that data from the source device can be interpreted by the appropriate application on the destination device.Compression of the data in a manner that can be decompressed by the destination device.Encryption of the data for transmission and the decryption of data upon receipt by the destination.

What is the main function of the session layer?

create and maintain dialogs between source and destination applications

3.1.1.3 What do the Application Layer protocols of the TCP/IP protocol specify?

the format and control information necessary for many of the common Internet communication functions

3.1.2 What are the two forms of software programs or process that provide network access in the Application Layer

applications and services

3.1.3 What do protocols provide? the rules and formats that govern how data is treatedWhat is the difference between an application and a service?

Applications interact with the user and services prepare data for the network

What do application layer protocols do?

Protocols provide the rules and formats that govern how data is treated.

3.1.4 What 6 things do protocols define?

1. processes on either end of the communication2. types of messages3. syntax of messages4. meaning of any informational fields5. how messages are sent and the expected

response6. interaction with the nextlower layer

3.2.1 What is the difference between a client and a server?

the device requesting the information is called a client and the device responding to the request is called a server

3.2.2 In general networking sense what is a server?

any device that responds to requests from client applications is functioning as a server

Describe the 2 processes a daemon uses (listening and hears)?

"listening" for a request from a client, because they are programmed to respond whenever the server receives a request for the service provided by the daemon"hears" a request from a client, it exchanges appropriate messages with the client, as required by its protocol, and proceeds to send the requested data to the client in the proper format

3.2.3.2 Complete the packet tracer lab examine a number of packets to see what each packet contains.

3.2.4 What is a peer-to-peer network? two or more computers are connected via a network and can share resources (such as printers and files) without having a dedicated server

Are peer-to-peer networks easy to No

secure?3.2.4.2 What are peer-to-peer

applications?allows a device to act as both a client and a server within the same communication

3.3.1 What do port numbers identify? applications and Application layer services that are the source and destination of data

What does the DNS protocol do? defines an automated service that matches resource names with the required numeric network address.

3.3.1.2 What does the nslookup utility allow you to do?

allows the user to manually query the name servers to resolve a given host name

What does the command ipconfig /displaydns show?

Displays all of the cached DNS entries on a Windows XP or 2000 computer system

3.3.1.3 What happens if a DNS server does not have a name in its stored records?

It passes the request on to another DNS server

If the same request is made again where does the DNS server look?

In its cache

3.3.1.4 When is a server declared to be an authoritative server?

When the resource is directly held on that server

3.3.2.1 Define the three parts of a url as listed on the page?

http:- protocolwww.cisco.com- name of serverweb-server.htm- name of file or page

What type of request is sent to the server when retrieving a web page?

GET

3.3.2.2 What does the POST command do?

Sends information to the web server

What does the PUT command do?

Sends resources or content to the web server

What protocol is used for secure transmission across the web?

HTTPS:

3.3.2.3 Packet Tracer Lab3.3.3 What 2 Application Layer

protocols are used in sending and receiving email?

POP (Post Office Protocol) and SMTP (Simple Mail Transfer Protocol)

What is another name for an email application?

MUA Mail User Agent

3.3.3.2 What are the two processes that email servers perform?

MTA Mail Transfer AgentMDA Mail Delivery Agent

3.3.3.3 What happens to emails in many companies once the email reaches the internal server?

Converted to a proprietary protocol for mail delivery

3.3.3.4 List and describe some of the commands used by the SMTP protocol.

HELO - identifies the SMTP client process to the SMTP server processEHLO - Is a newer version of HELO, which includes services extensionsMAIL FROM - Identifies the senderRCPT TO - Identifies the recipientDATA - Identifies the body of the message

3.3.4 What is File Transfer Protocol (FTP)?

developed to allow for file transfers between a client and a server

What are the 2 ports used and their purpose in FTP?

21- Used for control20- Used for actual file transfer

3.3.5 What does Dynamic Host Confirmation Protocol (DHCP) do for a network?

allows a host to obtain an IP address dynamically when it connects to the network

3.3.5.2 What are the 4 types of messages sent and received in DHCP?

DHCP DiscoverDHCP OfferDHCP RequestDHCP Acknowledge

3.3.6 What is SMB (Server Message Block)?

the structure of shared network resources, such as directories, files, printers, and serial ports

3.3.6.2 What are the 3 message types of SMB messages?

Start, authenticate, and terminate sessionsControl file and printer accessAllow an application to send or receive messages to or from another device

3.3.8 What does the Telenet application provide?

provides a standard method of emulating text-based terminal devices over the data network.

3.3.8.2 What protocol is recommended alternative to Telnet when security is a concern?

SSH (Secure Shell protocol)