nslookup is a command-line DNS query tool that ships with Windows and is also available on Linux and macOS. It sends a query to a resolver you choose and prints the answer, either as a one-off command or in an interactive mode.
Why it matters
Because it is installed on almost every Windows machine, it is often the first tool support teams reach for. It is simpler than dig but shows less: no flags, no per-section detail and limited control over recursion. The first lines of output name the server that answered, which helps spot a wrong resolver. A line saying "Non-authoritative answer" means the reply came from a cache, not the zone's own nameservers.
Example
> nslookup -type=MX example.com 1.1.1.1
Server: one.one.one.one
Address: 1.1.1.1
Non-authoritative answer:
example.com MX preference = 10, mail exchanger = mail.example.comInteractive mode starts by typing nslookup, then set type=TXT and a name.
Common mistakes
- Ignoring which resolver answered, then trusting a stale result.
- Using the old
set querytypehabit incorrectly. Useset type=. - Treating "Non-authoritative" as an error.
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