Summary

Chapter 8: Fundamental Networks 17with only other computers in the same range. An example of when these private addresseswould be useful is in a classroom lab where you want to prevent access outside to your network.This operating system feature is called Automatic Private IP Addressing (APIPA).APIPA continually requests an IP address from a DHCP server for your computer.Describe Internet Protocols and ApplicationsA protocol is a set of rules. Internet protocols are sets of rules governing communicationwithin and between computers on a network. Protocol specifications define the format ofthe 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 bewritten. 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 certainamount of time so that computers do not wait indefinitely for messages that may have beenlost. Therefore, systems maintain one or more timers during transmission of data. Protocolsalso initiate alternative actions if the network does not meet the timing rules. Many protocolsconsist of a suite of other protocols that are stacked in layers. These layers depend onthe operation of the other layers in the suite to function properly.These are the main functions of protocols:■■■■■Identifying errorsCompressing the dataDeciding how the data is to be sentAddressing the dataDeciding how to announce sent and received dataAlthough many other protocols exist, Table 8-1 summarizes the functions of some of themore common protocols used on networks and the Internet.Table 8-1ProtocolsProtocol FunctionsFunctionTCP/IPNetBEUI/NetBIOSIPX/SPXHTTP/HTTPSFTPTransports data on the InternetA small, fast protocol designed for a workgroup network thatrequires no connection to the InternetTransports data on a Novell NetWare networkDefines how files are exchanged on the webProvides services for file transfer and manipulationcontinues