Describe Internet Protocols and Applications

A protocol is a set of rules. Internet protocols are sets of rules governing communication within and between computers on a network. Protocol specifications define the format of the messages that are exchanged. A letter sent through the postal system also uses protocols. Part of the protocol specifies where on the envelope the delivery address needs to be written. If the delivery address is written in the wrong place, the letter cannot be delivered.

Timing is crucial to network operation. Protocols require messages to arrive within a certain amount of time so that computers do not wait indefinitely for messages that may have been lost. Therefore, systems maintain one or more timers during transmission of data. Protocols also initiate alternative actions if the network does not meet the timing rules. Many protocols consist of a suite of other protocols that are stacked in layers. These layers depend on the operation of the other layers in the suite to function properly.

These are the main functions of protocols:

■ Identifying errors

■ Compressing the data

■ Deciding how the data is to be sent

■ Addressing the data

■ Deciding how to announce sent and received data

Although many other protocols exist, Table 8-1 summarizes the functions of some of the more common protocols used on networks and the Internet.

Table 8-1 Protocol Functions




Transports data on the Internet


A small, fast protocol designed for a workgroup network that

requires no connection to the Internet


Transports data on a Novell NetWare network


Defines how files are exchanged on the web


Provides services for file transfer and manipulation


Table 8-1

Protocol Functions continued




Connects computers securely


Uses a text-based connection to a remote TCP/IP computer


Downloads e-mail messages from an e-mail server


Downloads e-mail messages from an e-mail server


Sends mail in a TCP/IP network

To understand how networks and the Internet work, you must be familiar with the commonly used protocols. These protocols are used to browse the web, send and receive e-mail, and transfer data files. You will encounter other protocols as your experience in IT grows, but they are not used as often as the common protocols described here:

■ TCP/IP: The TCP/IP suite of protocols has become the dominant standard for internetworking. TCP/IP represents a set of public standards that specify how packets of information are exchanged between computers over one or more networks.

■ IPX/SPX: Internetwork Packet Exchange/Sequenced Packet Exchange is the protocol suite originally employed by Novell Corporation's network operating system, NetWare. It delivers functions similar to those included in TCP/IP. Novell in its current releases supports the TCP/IP suite. A large installed base of NetWare networks continue to use IPX/SPX.

■ NetBEUI: NetBIOS Extended User Interface is a protocol used primarily on small Windows NT networks. NetBEUI cannot be routed or used by routers to talk to each other on a large network. NetBEUI is suitable for small peer-to-peer networks, involving a few computers directly connected to each other. It can be used in conjunction with another routable protocol such as TCP/IP. This gives the network administrator the advantages of the high performance of NetBEUI within the local network and the ability to communicate beyond the LAN over TCP/IP.

■ AppleTalk: AppleTalk is a protocol suite to network Macintosh computers. It is composed of a comprehensive set of protocols that span the seven layers of the Open Systems Interconnection (OSI) reference model. The AppleTalk protocol was designed to run over LocalTalk, which is the Apple LAN physical topology. This protocol is also designed to run over major LAN types, notably Ethernet and Token Ring.

■ HTTP: Hypertext Transfer Protocol governs how files such as text, graphics, sound, and video are exchanged on the World Wide Web (WWW). The Internet Engineering Task Force (IETF) developed the standards for HTTP.

■ FTP: File Transfer Protocol provides services for file transfer and manipulation. FTP allows multiple simultaneous connections to remote file systems.

■ SSH: Secure Shell is used to securely connect to a remote computer.

■ Telnet: An application used to connect to a remote computer that lacks security features.

■ POP3: Post Office Protocol is used to download e-mail from a remote mail server.

■ IMAP: Internet Message Access Protocol is also used to download e-mail from a remote mail server.

■ SMTP: Simple Mail Transfer Protocol is used to send e-mail to a remote e-mail server.

The more you understand about each of these protocols, the more you will understand how networks and the Internet work.

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  • Selamawit
    What are internet application protocols?
    6 months ago

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