In this chapter, our emphasis shifts from how TCP/IP functions to how it is configured. While Chapters Chapter 1 through Chapter 3 described the TCP/IP protocols and how they work, now we begin to explore the network configuration process. The first step in this process is planning. Before configuring a host to run TCP/IP, you must have certain information. At the very least, every host must have a unique IP address and hostname. You should also resolve the following issues before configuring a system:
If the system communicates with TCP/IP hosts that are not on its local network, a default gateway address may be needed. Alternatively, if a routing protocol is used on the network, each device needs to know that protocol.
To resolve hostnames into IP addresses, each host needs to know the addresses of the domain name servers.
Hosts using the domain name system must know their correct domain name.
To communicate properly, each system on a network must use the same subnet mask.
If you're adding a system to an existing network, make sure you find out the answers from your network administrator before putting the system online. The network administrator is responsible for making and communicating decisions about overall network configuration. If you have an established TCP/IP network, you can skip several sections in this chapter, but you may still want to read about selecting hostnames, planning mail systems, and other topics that affect mature networks as much as they do new networks.
If you are creating a new TCP/IP network, you will have to make some basic decisions. Will the new network connect to the Internet? If so, how will the connection be made? How should the network number be chosen? How do I register a domain name? How do I choose hostnames? In the following sections, we cover the information you need to make these decisions.