What is nslookup?
Nslookup.exe is a command-line administrative tool for testing and troubleshooting DNS servers. This tool is installed along with the TCP/IP protocol through Control Panel. Nslookup.exe can be run in two modes: interactive and noninteractive. Noninteractive mode is useful when only a single piece of data needs to be returned. Before using Nslookup.exe, you should keep the following in your mind:
1. The TCP/IP protocol must be installed on the computer running Nslookup.exe
2. At least one DNS server must be specified when you run the IPCONFIG /ALL command from a command prompt.
3. Nslookup will always devolve the name from the current context. If you fail to fully qualify a name query (that is, use trailing dot), the query will be appended to the current context. For example, the current DNS settings are att.com and a query is performed on www.microsoft.com; the first query will go out as www.microsoft.com.att.com because of the query being unqualified. This behavior may be inconsistent with other vendor's versions of Nslookup, and this article is presented to clarify the behavior of Microsoft Windows NT Nslookup.exe
4. If you have implemented the use of the search list in the Domain Suffix Search Order defined on the DNS tab of the Microsoft TCP/IP Properties page, devolution will not occur. The query will be appended to the domain suffixes specified in the list. To avoid using the search list, always use a Fully Qualified Domain Name, that is, add the trailing dot to the name.
How to use nslookup?
To start Nslookup.exe in interactive mode:
1. Click Start.
2. Click Run.
3. Type cmd
4. Type "nslookup" at the command prompt. The following screen will appear:
C:\> nslookup
Default Server: nameserver1.domain.com
Address: 10.0.0.1
>
To start Nslookup.exe in noninteractive mode:
1. Click Start.
2. Click Run.
3. Type cmd
4. Type the following command at the command prompt:
nslookup [-option] [hostname] [server]
