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2012-05-18

A+: LANs, Internet Connectivity and Network Protocols

A LAN is an ideal way to provide Internet access to two or more users. However, a LAN by itself cannot connect to the Internet. Two additional components must also be used with a LAN to enable it to connect to the Internet:

    • An Internet access device— This could be a dial-up modem, but more often a broadband connection such as DSL, cable, or satellite is used.

    • A router—This device connects client PCs on the network to the Internet through the Internet access device. To the Internet, only one client is making a connection, but the router internally tracks which PC has made the request and transmits the data for that PC back to that PC, enabling multiple PCs to access the Internet through the network.

As an alternative to a router and modem or codec, some small networks use a gateway, which is a PC configured to share its Internet connection with others on the network. Windows 2000 and later versions support this feature, known as Internet Connection Sharing. Note that wireless access devices known as gateways actually resemble routers.


Network Protocols


The 2009 A+ Certification Exams expect you to understand the major features of network protocols TCP/IP and NetBEUI/NetBIOS.Although most current networks are based on TCP/IP, you might encounter others in some networks.


TCP/IP is short for Transport Control Protocol/Internet Protocol. It is a multiplatform protocol used for both Internet access and for local area networks. TCP/IP is used by Novell NetWare 5.x and later and Windows Vista/XP/2000 as the standard protocol for LAN use, replacing NetBEUI (used on older Microsoft networks) and IPX/SPX (used on older versions of Novell NetWare). Using TCP/IP as a network’s only protocol makes network configuration easier because users need to configure only one protocol to communicate with other network clients, servers, or with the Internet.
   
Most networking you’ll perform in the real world uses TCP/IP. TCP/IP is also the most complex network to configure, especially if you need to use a static IP address.


NetBEUI (NetBIOS Extended User Interface), the simplest protocol, is an enhanced version of an early network protocol called NetBIOS (NetBIOS itself is no longer used for this purpose). Historically, NetBEUI was used primarily on peer networks using Windows, with direct cable connection between two computers, and by some small networks that use Windows NT Servers. NetBEUI lacks features that enable it to be used on larger networks: It cannot be routed or used to access the Internet.

NetBEUI is not officially supported in Windows XP or Vista, although Microsoft provides the NetBEUI protocol on the XP distribution CD in the Valueadd\MSFT\Net\NetBEUI folder for use with older networks or for troubleshooting. For details on how to install NetBEUI in Windows XP, see the Microsoft Knowledge Base article 301041 available at http://support.microsoft.com/kb/301041. NetBIOS can be used in conjunction with TCP/IP in Windows XP and Vista.


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