Windows XP in a Nutshell, Second Edition

Name

NSLookup — \windows\system32\nslookup.exe

Synopsis

Perform a Domain Name Server (DNS) lookup, used to convert domain names to IP addresses, and vice versa.

To Open

Command Prompt → nslookup

Usage

nslookup address

Description

When you type a web address into a browser’s address bar and press Enter, Windows looks up the server name to determine the corresponding IP address. Then the IP address is used to initiate communication with the server. If the lookup fails, either because the name servers (the machines containing the DNS lookup tables) are down or because the specified domain does not exist, the connection attempt will fail as well.

NSLookup is a simple tool that allows you to look up the IP address of any domain name or server name, as well as find the server name associated with any particular IP address. To use NSLookup, just specify the domain name at the prompt, like this:

c:\> nslookup annoyances.org
Name:    annoyances.org
Address:  209.133.53.130

Likewise, you can specify an IP address and NSLookup will report the associated domain (called a reverse lookup):

c:\> nslookup 209.204.146.22
Name:    www.oreilly.com
Address:  209.204.146.22

Notes

• Every time you initiate communication with a server, there will be a delay while Windows performs an NSLookup. To eliminate the delay, use NSLookup to determine the IP address and then replace the reference with the IP address. This is especially useful with applications that frequently access the same server; for example, use an IP address ...