Sim-Ex™ Tutorial for Network+

2.0 Protocols and standards

  1. Layers of OSI
  2. MAC Address
  3. Subnetting
  4. Public and Private Networks
  5. TCP/IP Protocols
  6. Network Utilities

2.5 TCP/IP Protocols

A Protocol is a predefined set of rules that dictates how network devices (such as router, computer, or switch) communicate and exchange data on the network.

Application Protocols:

The Application Protocol are built on the top of TCP/IP protocol suite. The list of protocol include the following:

Simple Network Management Protocol (SNMP) : The Simple Network Management Protocol (SNMP) is an application-layer protocol designed to manage complex communication networks. SNMP works by sending messages, called protocol data units (PDUs), to different parts of a network. SNMP-compliant devices, called agents, store data about themselves in Management Information Bases (MIBs) and return this data to the SNMP servers.

There are two versions of SNMP: Version 1 and Version 2.

File Transfer Protocol (FTP) : FTP is a Client Server protocol, used for copying files between an FTP server and a client computer over a TCP/IP network. FTP is commonly used to communicate with web servers to upload or download files.

FTP, the File Transfer Protocol, documented in RFC 959, is one of oldest Internet protocols still in widespread use. FTP uses TCP protocol for communication, and capable of transferring both binary files and text files. Some popular FTP clients include FileZilla, and cuteFTP.

FTP uses port TCP port number 21.

Trivial File Transfer Protocol (TFTP) : TFTP stands for Trivial File Transfer Protocol. TFTP is very similar to FTP, but uses UDP protocol for file transfer. UDP, as discusses elsewhere in the tutorial is considered to an unreliable protocol. Hence, TFTP is not frequently used for normal file transfer applications.

Simple Mail Transfer Protocol (SMTP) : SMTP (Simple Mail Transfer Protocol) is a TCP/IP protocol used for sending e-mail messages between servers. SMTP is also used to send email messages from a client machine to a server. An email client such as MS Outlook Express uses SMTP for sending emails and POP3/IMAP for receiving emails from the server to the client machine. In other words, we typically use a program that employs SMTP for sending e-mail, and either POP3 or IMAP for receiving messages from our local (or ISP) server. SMTP is usually implemented to operate over Transmission Control Protocol port 25.

Post Office Protocol (POP3) : POP3 stands for Post of Protocol version 3. It is used for fetching messages from an email server. Most commonly used POP3 client programs include Outlook Express, and Mozilla Thunderbird.

Internet Message Access Protocol (IMAP) : The Internet Message Access Protocol (commonly known as IMAP or IMAP4) allows a local client to access e-mail on a remote server. The current version, IMAP version 4 is defined by RFC 3501. IMAP4 and POP3 are the two most prevalent Internet standard protocols for e-mail retrieval.

Network File System (NFS) : Network File System is a distributed file system which allows a computer to transparently access files over a network.

Telnet : The Telnet service provides a remote login capability. This lets a user on one machine log into another machine and act as if they are directly in front of the remote machine. The connection can be anywhere on the local network, or on another network anywhere in the world, as long as the user has permission to log into the remote system. Telnet uses TCP to maintain a connection between two machines. Telnet uses port number 23.

Hypertext Transfer Protocol (HTTP) : A protocol used to transfer hypertext pages across the World Wide Web. HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. For example, when you enter a URL in your browser, this actually sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page. Note that HTML deals with how Web pages are formatted and displayed in a browser.

HTTP is called a stateless protocol because each command is executed independently, without any knowledge of the commands that came before it.

Network News Transfer Protocol (NNTP) : A protocol used to carry USENET posting between News clients and USENET servers.

Line Printer Daemon (LPD), Line Printer Remote (LPR) : LPD, LPR are used for serving, and printing using Unix server computes.

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