Summary

18 IT Essentials: PC Harware and Software Companion GuideTable 8-1 Protocol Functions continuedProtocolsSSHTelnetPOP3IMAPSMTPFunctionConnects computers securelyUses a text-based connection to a remote TCP/IP computerDownloads e-mail messages from an e-mail serverDownloads e-mail messages from an e-mail serverSends mail in a TCP/IP networkTo understand how networks and the Internet work, you must be familiar with the commonlyused protocols. These protocols are used to browse the web, send and receive e-mail, andtransfer data files. You will encounter other protocols as your experience in IT grows, butthey 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 informationare exchanged between computers over one or more networks.IPX/SPX: Internetwork Packet Exchange/Sequenced Packet Exchange is the protocolsuite originally employed by Novell Corporation’s network operating system, NetWare.It delivers functions similar to those included in TCP/IP. Novell in its current releasessupports the TCP/IP suite. A large installed base of NetWare networks continue to useIPX/SPX.NetBEUI: NetBIOS Extended User Interface is a protocol used primarily on smallWindows NT networks. NetBEUI cannot be routed or used by routers to talk to eachother on a large network. NetBEUI is suitable for small peer-to-peer networks, involvinga few computers directly connected to each other. It can be used in conjunctionwith another routable protocol such as TCP/IP. This gives the network administrator theadvantages of the high performance of NetBEUI within the local network and the abilityto communicate beyond the LAN over TCP/IP.AppleTalk: AppleTalk is a protocol suite to network Macintosh computers. It is composedof a comprehensive set of protocols that span the seven layers of the OpenSystems Interconnection (OSI) reference model. The AppleTalk protocol was designedto run over LocalTalk, which is the Apple LAN physical topology. This protocol is alsodesigned 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 EngineeringTask Force (IETF) developed the standards for HTTP.FTP: File Transfer Protocol provides services for file transfer and manipulation. FTPallows multiple simultaneous connections to remote file systems.