Nslookup

Nslookup (Nslookup.exe) is the primary tool for isolating DNS name resolution problems when connected to the client experiencing the problems. Nslookup is a command-line tool capable of performing DNS lookups and reporting on the results. Other tools, such as PathPing, are capable of resolving host names to IP addresses and displaying the results, but only Nslookup displays the DNS server used to resolve the request. Additionally, Nslookup displays all the results returned by the DNS server and allows you to choose a specific DNS server rather than using the server automatically chosen by Windows.

Nslookup is the correct tool to use when troubleshooting the following types of problems:

• Clients take several seconds to establish an initial connection.
• Some clients can establish a connection to a server, but other clients experience problems.
• The DNS server is configured correctly, but clients are resolving host names incorrectly.

Note The Hosts file, located in the %WinDir%\System32\Drivers\Etc folder, might contain static entries that override DNS lookups for most applications. Nslookup ignores this file, however. If applications resolve a host name differently than Nslookup, verify that the Hosts file does not contain an entry for the host name.