Term
| What does the application layer provide? |
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Definition
| provides the interface between the applications we use to communicate and the underlying network over which our messages are transmitted |
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Term
| What are application layer protocols used for? |
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Definition
| to exchange data between programs running on the source and destination hosts |
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Term
| What are the three primary functions of the Presentation Layer? |
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Definition
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. |
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Term
| What is the main function of the session layer? |
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Definition
| create and maintain dialogs between source and destination applications |
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Term
| What do the Application Layer protocols of the TCP/IP protocol specify? |
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Definition
Domain Name Service Protocol (DNS) is used to resolve Internet names to IP addresses.
Hypertext Transfer Protocol (HTTP) is used to transfer files that make up the Web pages of the World Wide Web.
Simple Mail Transfer Protocol (SMTP) is used for the transfer of mail messages and attachments.
Telnet, a terminal emulation protocol, is used to provide remote access to servers and networking devices.
File Transfer Protocol (FTP) is used for interactive file transfer between systems. |
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Term
| What are the two forms of software programs or process that provide network access in the Application Layer |
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Definition
| Applications and Services |
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Term
| What do protocols provide? |
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Definition
| Rules and formats that govern how the data is treated |
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Term
| What is the difference between an application and a service? |
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Definition
applications provide people with a way to create messages
services establish an interface to the network |
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Term
| What do application layer protocols do? |
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Definition
| protocols specify what messages are exchanged between the source and destination hosts |
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Term
| What 6 things do protocols define? |
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Definition
Processes on either end of the communication
The types of messages
The syntax of messages
The meaning of any informational fields
How messages are sent and the expected response
Interaction with the next lower layer |
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Term
| What is the difference between a client and a server? |
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Definition
| he device requesting the information is called a client and the device responding to the request is called a server |
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Term
| In general networking sense what is a server? |
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Definition
| A server is usually a computer that contains information to be shared with many client systems. For example, web pages, documents, databases, pictures, video, and audio files can all be stored on a server and delivered to requesting clients. In other cases, such as a network printer, the print server delivers the client print requests to the specified printer. |
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Term
| Describe the 2 processes a daemon uses (listening and hears)? |
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Definition
| as "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 |
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Term
| Complete the packet tracer lab examine a number of packets to see what each packet contains. |
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Definition
| When a 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. |
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Term
| What is a peer-to-peer network? |
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Definition
| Peer-to-peer networking involves two distinct forms: peer-to-peer network design and peer-to-peer applications (P2P). |
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Term
| Are peer-to-peer networks easy to secure? |
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Definition
| No because the users have all the control |
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Term
| What are peer-to-peer applications? |
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Definition
| Allows a device to act as both a client and a server within the same communication |
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Term
| What do port numbers identify? |
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Definition
| identify applications and Application layer services that are the source and destination of data |
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Term
What does the DNS protocol do?
(Domain Name System) |
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Definition
DNS protocol defines an automated service that matches resource names with the required numeric network address. It includes the format for queries, responses, and data formats.
DNS protocol communications use a single format called a message. This message format is used for all types of client queries and server |
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Term
| What does the nslookup utility allow you to do? |
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Definition
| allows the user to manually query the name servers to resolve a given host name |
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Term
| What does the command ipconfig /displaydns show? |
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Definition
| displays all of the cached DNS entries on a Windows XP or 2000 computer system |
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Term
| What happens if a DNS server does not have a name in its stored records? |
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Definition
| If it is unable to resolve the name using its stored records, it contacts other servers in order to resolve the name. |
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Term
| If the same request is made again where does the DNS server look? |
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Definition
| the first server can return the address by using the value stored in its name cache |
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Term
| When is a server declared to be an authoritative server? |
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Definition
| If a given server has resource records that correspond to its level in the domain hierarchy, |
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Term
| Define the three parts of a url as listed on the page? |
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Definition
1. http (the protocol or scheme)
2. www.cisco.com (the server name)
3. web-server.htm (the specific file name requested). |
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Term
| What type of request is sent to the server when retrieving a web page? |
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Definition
| web clients make connections to the server and request the desired resources. |
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Term
| What does the POST command do? |
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Definition
| to send messages that upload data to the web server |
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Term
| What does the PUT command do? |
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Definition
| uploads resources or content to the web server. |
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Term
| What protocol is used for secure transmission across the web? |
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Definition
| HTTP is used across the World Wide Web for data transfer and is one of the most used application protocols. |
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Term
| What 2 Application Layer protocols are used in sending and receiving email? |
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Definition
Post Office Protocol (POP)
Simple Mail Transfer Protocol (SMTP) |
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Term
| What is another name for an email application? |
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Definition
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Term
| What are the two processes that email servers perform? |
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Definition
Mail Transfer Agent (MTA)
Mail Delivery Agent (MDA) |
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Term
| What happens to emails in many companies once the email reaches the internal server? |
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Definition
| communicate with the e-mail server using a proprietary protocol. The server sends or receives e-mail via the Internet through the product's Internet mail gateway, which performs any necessary reformatting. |
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Term
| List and describe some of the commands used by the SMTP protocol. |
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Definition
HELO - identifies the SMTP client process to the SMTP server process,
EHLO - Is a newer version of HELO, which includes services extensions,
MAIL FROM - Identifies the sender,
RCPT TO - Identifies the recipient,
DATA - Identifies the body of the message |
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Term
| What is File Transfer Protocol (FTP)? |
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Definition
| is another commonly used Application layer protocol. FTP was developed to allow for file transfers between a client and a server. An FTP client is an application that runs on a computer that is used to push and pull files from a server running the FTP daemon |
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Term
| What are the 2 ports used and their purpose in FTP? |
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Definition
The client establishes the first connection to the server on TCP port 21. This connection is used for control traffic, consisting of client commands and server replies.
The client establishes the second connection to the server over TCP port 20. This connection is for the actual file transfer and is created every time there is a file transferred. |
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Term
| What does Dynamic Host Confirmation Protocol (DHCP) do for a network? |
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Definition
| enables devices on a network to obtain IP addresses and other information from a DHCP server. This service automates the assignment of IP addresses, subnet masks, gateway and other IP networking parameters. |
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Term
| What are the 4 types of messages sent and received in DHCP? |
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Definition
| DHCP Discover, DHCP Offer, DHCP Request, DHCP Acknowledge |
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Term
| What is SMB (Server Message Block)? |
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Definition
| a client/server file sharing protocol. IBM developed Server Message Block (SMB) in the late 1980s to describe the structure of shared network resources |
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Term
| What are the 3 message types of SMB messages? |
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Definition
Start, authenticate, and terminate sessions
Control file and printer access
Allow an application to send or receive messages to or from another device |
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Term
| What does the Telenet application provide? |
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Definition
| Telnet provides a standard method of emulating text-based terminal devices over the data network. Both the protocol itself and the client software that implements the protocol are commonly referred to as Telnet. |
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Term
| What protocol is recommended alternative to Telnet when security is a concern? |
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Definition
| The Secure Shell (SSH) protocol offers an alternate and secure method for server access. |
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