What is the nslookup command used for?

nslookup lets you manually query DNS servers to resolve a name and troubleshoot name resolution; run with no parameters it shows your host's default DNS server.

The nslookup Command:

A computer operating system utility that allows users to manually query DNS servers to resolve domain names.

* nslookup makes this query visible: client asks the local server, which forwards up the hierarchy if needed, then caches the answer. *

Uses:

• Troubleshoot name resolution issues
• Verify the current status of name servers
• Query specific DNS records

Basic usage:

C:\> nslookup
Default Server: dns-sj.cisco.com
Address: 171.70.168.183

> www.cisco.com
Server: dns-sj.cisco.com
Address: 171.70.168.183

Name:    www.cisco.com
Address: 23.1.48.170

Additional command:

ipconfig /displaydns

Displays all cached DNS entries on a Windows PC.

Key insight: When nslookup is issued without parameters, it displays the default DNS server configured for your host.

Go deeper:

• nslookup (Wikipedia) — the DNS query tool, its modes, and how it differs from dig.