Workshop

Previous Table of Contents Next
Because a socket is the equivalent of a phone extension, the program that picks up the call is the
equivalent of the person within the house or company that you want to talk to (see Figure 1.4). The
program can do things for you once you “talk”—either give you information or kick off a process that
you need accomplished. Some requests can be a combination of both: When you search the Internet, you
ask the program on the other end to do a search, and you ask for the answer to your search.
Figure 1.4 A socket is the equivalent of a phone extension.
Just like people, some programs (also called services because they’re server programs) on the other side
of the line speak only one language. For example, standard Web servers speak only TCP/IP. However, as
previously mentioned, Microsoft file and print sharing services can run on just about anything: TCP/IP,
IPX/SPX, and NetBEUI. As with teaching a person a new language, it takes a bunch of effort to program
multiple-protocol support into a service, and unless there’s payback involved, most programs just pick
one protocol and stick with it. The most popular protocol for modern programs? You guessed it: TCP/IP.
What’s in a Name?
You’ve probably asked yourself in one of the preceding paragraphs, “How does www.co.chatham.ga.us
get translated into 167.195.160.9?” Furthermore, why use names at all? People can deal with phone
numbers, why not just use the IP number? These are good questions. The answer to the latter is that just
because people can deal with a number doesn’t mean that they prefer to use a number. Which would you
rather remember, 1-800-NETWORK or 1-800-638-9675? Obviously, most people prefer to remember a
name. Actually, names are the better thing to use when networking, because numerical addresses can
change during a reconfiguration or a move, whereas symbolic names typically stay the same.
Name-to-address translation (also known as name lookup or name resolution) occurs via name services.
Very similar to the speed dial button on your phone, name services are the networking equivalent of an
electronic phone book. They’re actually a lot cooler than your speed dial: For example, suppose you
could say “Mom” to make your phone dial your mother.
DNS
Name services run as a service on any given name server; that is, a specific program runs on a name
server that hands out an address when you give it a name. Like your speed dial buttons, you must