Windows XP (as well as NT and 2000) comes with two versions of DOS. Command.com is an old DOS version. Various versions of command.com come with Windows 95, 98, SE, ME, Window 3, and DOS only operating systems.

The other DOS, which comes only with the XP, 2000 and NT operating systems, is cmd.exe. Usually cmd.exe is better than command.com because it is easier to use, has more commands, and in some ways resembles the bash shell in Linux and other Unix-type operating systems. For example, you can repeat a command by using the up arrow until you back up to the desired command. Unlike bash, however, your DOS command history is erased whenever you shut down cmd.exe. The reason XP has both versions of DOS is that sometimes a program that won’t run right in cmd.exe will work in command.com

So how do you turn on DOS?
Click on Programs -> Accessories -> Command Prompt
That runs cmd.exe. You should see a black screen with white text on it, saying something like this:

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\>

You can now find out what commands you can run in DOS. If you type "help" at the DOS prompt, it gives you a long list of commands. However, this list leaves out some commands (Microsoft belives what you don’t know makes Windows more secure). Here are some of those left out commands.

TCP/IP commands:
telnet
netstat
nslookup
tracert
ping
ftp

NetBIOS commands (just some examples):
nbtstat
net use
net view
net localgroup

TCP/IP stands for transmission control protocol/Internet protocol. As you can guess by the name, TCP/IP is the protocol under which the Internet runs. along with user datagram protocol (UDP). Most local area networks also use TCP/IP.

NetBIOS (Net Basic Input/Output System) protocol is another way to communicate between computers. This is often used by Windows computers, and by Unix/Linux type computers running Samba. You can often use NetBIOS commands over the Internet (being carried inside of, so to speak, TCP/IP). Not many Internet computers run NetBIOS because it is so easy to break in using them.