The nslookup command is really easy to use. You just type nslookup [host-name] and you get an answer. But what do you do when it looks like it is working, but your monitoring is detecting intermittent issues connecting to a website? The answer is, you check each nameserver individually to make sure they are all giving out the same answer.
Find the Nameservers with NSLOOKUP
Let’s look up the nameservers for our website. We’ll usually get back multiple answers. Two or three is pretty common. We can use nslookup -querytype=ns [root domain] to do this.
C:\>nslookup -querytype=ns stevefenton.co.uk Server: UnKnown Address: 1.1.1.1 Non-authoritative answer: stevefenton.co.uk nameserver = dane.ns.cloudflare.com stevefenton.co.uk nameserver = amy.ns.cloudflare.com
Check Each Nameserver with NSLOOKUP
This is how you look up records from a specific name server. It uses the syntax nslookup [host-name] [nameserver]. You can supply the name of the nameserver: nslookup www.stevefenton.co.uk amy.ns.cloudflare.com, or its IP address: nslookup www.stevefenton.co.uk 2a06:98c1:50::ac40:2065.
C:\>nslookup www.stevefenton.co.uk amy.ns.cloudflare.com
Server: amy.ns.cloudflare.com
Address: 2a06:98c1:50::ac40:2065
Name: www.stevefenton.co.uk
Addresses: 104.31.65.119
104.31.64.119
172.67.196.210
Repeat this for each nameserver and keep an eye out for any that are giving out bad answers.
NSLOOKUP Tips
And finally, some quick nslookup tips.
Simple DNS Check
nslookup [host-name] nslookup www.example.com
Specific Record Type Check
nslookup -querytype=[record-type] [host-name] nslookup -querytype=mx example.com
Nameserver Lookup
nslookup -querytype=ns [host-name] nslookup -querytype=ns example.com
DNS Check Against Specific Nameserver
nslookup [host-name] [nameserver] nslookup www.example.com a.iana-servers.net