NSLookup

NSLookup is a tool that lets you enter a hostname (for example, "www.yahoo.com") and find out the corresponding IP address. It will also do reverse name lookup and find the hostname for an IP address you specify. Such conversion of hostnames to IP addresses and vice versa is the main NSLookup function; however, advanced users can also use it to perform specific queries, e.g. queries for Mail Exchange (MX) records. NSLookup works by sending a Domain Name System (DNS) query to your default DNS server (in case of the Standard Resolve Function), or to any DNS server you specify (in case of all other query types).

To perform the standard query, select Standard Resolve Function from the Query type list, enter an IP address or hostname in the Query field, and click Start. The program will display the query result in a few seconds. For standard queries, the program will always contact your default DNS server, so the Name server field is disabled.

To perform non-standard queries, select the type of record you are requesting from the Query type list, enter your query in the Query field, and enter a DNS server address in the Name server field. When you run the program for the first time, the Name server drop-down list contains the list of your default DNS servers; you can select one from the list, or enter an arbitrary one, e.g. "ns1.pair.com".

NSLookup offers many query types to choose from, and it takes some understanding of the Internet to perform any queries other than Standard Resolve Function. If you are a beginner and want to learn more about various query types, we suggest reading RFC 1034 and RFC 1035, or searching the web for query type names.

Right-clicking on the window brings up a menu with the following commands: