I personally use command prompt to map network drives using the net use command, I also use it to run chkdsk /f command (which schedules a chkdsk to run at next boot). You can use cmd prompt to move, delete files that are giving you problems.
CMD prompt is very useful. Here is a page I used to open the doors of cmd prompt:
http://www.amset.info/windows/dosprompt.asp
If you mean a Command Prompt Command then there are a few you can use. The most commonly used would be ping and tracert. But there are others including netstat which shows the port status.
PROMPT command is an internal command, which is used to change the MS-DOS prompt. Through, the system displays the prompt bu default, when you start the computer.
exit
Open a command prompt window then type in ipconfig/all Then there should be your dns server.
If you have an antivirus program, you have that option when initializing that program to run. No reason to do it from the command prompt. The Command Prompt is only used when there are systems needed to be accessed for maintenance or system changes that need to be done within the "shell" of the OS. command is sfc /scannow
edit
Nslookup
AT
CLS means CLear Screen. it is a command used in command prompt
start -> Run -> regedit
taskview/svc
the command prompt is a program where you can command the computer to perform functions such as shutdown, restart, open a certain file, start a program, etc.