nslookup is a network administration command-line tool available for many computer operating systems for querying the Domain Name System (DNS) to obtain domain name or IP address mapping or for any other specific DNS record.
As of BIND 9.9.0a3, nslookup has apparently been resurrected ("nslookup is no longer to be treated as deprecated"). (The Internet Systems Consortium had previously deprecated nslookup in favor of host and dig for some time.)
The name "nslookup" means "name server lookup". nslookup does not use the operating system's local Domain Name System resolver library to perform its queries, and thus may behave differently to dig (which does). Additionally, vendor-provided versions can confuse matters by using or including output of other sources of name information (such as host files, Network Information Service). Some behaviors of nslookup may be modified by the contents of resolv.conf.
nslookup operates in interactive or non-interactive mode. When used interactively by invoking it without arguments or when the first argument is - (minus sign) and the second argument is a host name or Internet address of a name server, the user issues parameter configurations or requests when presented with the nslookup prompt (
>). When no arguments are given, then the command queries the default server. The - (minus sign) invokes subcommands which are specified on the command line and should precede nslookup commands. In non-interactive mode, i.e. when the first argument is a name or Internet address of the host being searched, parameters and the query are specified as command line arguments in the invocation of the program. The non interactive mode searches the information for a specified host using the default name server.
- whois, query tool for Internet domains and IP addresses
- "BIND 9.9.0a3 Release Notes". isc.org. 2011-10-19. Retrieved 2014-01-21.
- "nslookup is dead, long live dig and host | smalley creative blog". Blog.smalleycreative.com. 2011-01-06. Retrieved 2012-09-05.
- "BIND 9.5 Administrator Reference Manual | Internet Systems Consortium". Isc.org. Retrieved 2012-09-05.
- "DNS and BIND, Fourth Edition: Chapter 12. nslookup and dig". O'Reilly. Retrieved 20 July 2010.
- "pSeries and AIX Information Center". Publib.boulder.ibm.com. Retrieved 2012-09-05.
- Microsoft Windows
- Unix-like OSs