Nslookup command explained
There is plenty of command-line interface software for network diagnostics out there. One of the commonly used is nslookup. Why? Because it is simple, yet useful. It has a set of functions for checking different DNS records and DNS servers.
You can find it on various OSes like Windows, of course, but also many Linux distros, some Unix-based OSes (macOS), and ReactOS.
Network administrators can use it simultaneously with other software and receive diverse network data.
There are also websites that provide many online diagnostics tools like nslookup online. They could be useful because you don’t depend on the OS of your device, but bear in mind you should use just well-recognized sites for better security.
How to open nslookup?
To open nslookup on Windows 10:
You need to run the command prompt. Go to Start, then Run, type in “cmd” and press enter. In the Command prompt write nslookup and click Enter. Ready!
*Nslookup works differently on different OSes. We recommend that you use it on Linux or macOS for full functionality.
To open nslookup on Linux:
Start the Terminal and type in “nslookup”. Then press Enter and you are all set!
To open nslookup on macOS:
Go to applications and search for the Terminal. Open it and write “nslookup” followed by a press of the Enter button. Done!
Nslookup commands, examples
We are using Google.com for our examples, but you can change it with the domain you’d like to check out.
Search for the A records of а particular domain
Use nslookup to create a query for the A records of a domain. That way you can see all the IP addresses related to the domain.
Check the NS records of a specific domain
By executing this command, you will see the authoritative server for the selected domain. It is written on the NS records
nslookup -type=ns google.com
Check the SOA record
SOA is the start of authority. In the SOA record you can get the zone information.
nslookup -type=soa google.com
Nslookup for MX records
You can use nslookup to check the MX records and verify if the mail servers are working properly.
nslookup -query=mx google.com
Look at all the DNS records of a domain
You want to see all the DNS records, use this command. Later you can check any of the available DNS records, one by one if you like.
nslookup -type=any google.com
Check a specific ns server for the selected domain
You can also use this admin tool to check a specific ns server. You can see if it is responsive or not.
nslookup example.com ns1.google.com
Reverse DNS Lookup with nslookup
Sometimes you don’t need the IP address of a domain, but you want to see if an IP really corresponds to a specific domain. Then you use a reverse DNS lookup with the IP address in question.
A specific port in use
See if a particular port is in use. Maybe you want to verify that you’ve limited a certain port. An nslookup for that port should do the trick. In our case, it will be port 53.
nslookup -port=53 example.com
Timeout of the query
You can change the time interval to more seconds if you want to give more time to the server. Also, you can limit the time to see which servers respond fast enough. In our example, it is 15 seconds.
nslookup -timeout=15 google.com
Debug mode enable
You can enable the Debug mode which will give you detailed information about the question and the received answer.
nslookup -debug google.com
So, nslookup is a small tool, a command-line that you can use for different purposes. You can see a lot of information about DNS records of your domain.