Nslookup (name server lookup) is a command-line utility that is used to diagnose and verify DNS servers and records, and detect problems with resolving names in the DNS subsystem. The nslookup utility was originally developed as part of the BIND package and ported to Windows by Microsoft. At this moment Nslookup is a built-in tool in all supported versions of Windows OS.
How to Use Nslookup to Check DNS Records?
Using the nslookup utility, you can determine the IP address of any server by its DNS name, perform the reverse conversion (reverse DNS lookup), get information about the various DNS records of the specific domain name.
When running, Nslookup sends queries to the DNS server that is specified in the settings of your network connection. This address is considered as a default (preferred) DNS server. The user can specify the address of any other available DNS server. As a result, all the following DNS queries will be sent on it.
You can use the nslookup utility in interactive or non-interactive mode.
To run a DNS query using nslookup tool in non-interactive mode, open a Command prompt and run the command:
In this example, we requested the IP address of theitbros.com domain. The nslookup utility queries the DNS server (it is specified in the Server line) and it returned that this name corresponds to the IP address 18.104.22.168.
Such a response indicates that your DNS server is available, works properly and processes requests for resolving DNS names.
If you received such an answer:
Server: dns1.contoso.com Address: хх.хх.хх.хх *** dns1.contoso.com can't find theitbros.com: Non-existent domain
This means that no entries in the DNS zone have been found for this name.
If your DNS server is unavailable or not responding, you will receive a DNS request timed out error.
In this case, check if you have specified the correct DNS server address and whether there is a problem with the network connection from the IS provider.
The Non-authoritative answer means that the DNS server that executed the request is not the owner of the theitbros.com zone (there are no records about this domain in its database), and to perform name resolution a recursive query to another DNS server was used.
You can access an authoritative server by specifying its address directly in the parameters of the nslookup utility. For example, to resolve a name on the authoritative DNS server (that contains this domain) use the command:
Nslookup theitbros.com ns1.theitbros.com
When you run nslookup without parameters, the utility switches to the interactive mode. In this mode, you can execute various commands. A complete list of available internal commands of the nslookup utility can be displayed by typing a question.
Tip. Note that the commands of the nslookup utility are case sensitive.
To close nslookup interactive session, type exit and press Enter.
To find the DNS servers that are responsible for a specific domain (authoritative servers), run the following commands:
set query=ns theitbros.com
You can perform the reverse queries (get DNS name by IP address), just type the IP address in the nslookup interactive prompt and press Enter.
You can specify the type of DNS records that nslookup should return. For example, to list all mail servers configured for a particular domain, run the command:
nslookup -type=mx theitbros.com
Non-authoritative answer: theitbros.com MX preference = 10, mail exchanger = mail.theitbros.com theitbros.com MX preference = 20, mail exchanger = mail.theitbros.com mail.theitbros.com internet address = 22.214.171.124 mail.theitbros.com internet address = 126.96.36.199
As you can see, this domain has 2 MX records with priorities 10 and 20 (the lower the number, the higher the priority of the address). If the MX record is not displayed, it’s likely that they are simply not configured for this domain.
To list all DNS records in the domain zone, run the command:
nslookup -type=any theitbros.com
Non-authoritative answer: theitbros.com internet address = 188.8.131.52 theitbros.com nameserver = ns2.theitbros.com theitbros.com nameserver = ns1.theitbros.com theitbros.com MX preference = 10, mail exchanger = mail.theitbros.com theitbros.com MX preference = 20, mail exchanger = mail.theitbros.com ns2.theitbros.com internet address = 184.108.40.206 ns1.theitbros.com internet address = 220.127.116.11 mail.theitbros.com internet address = 18.104.22.168 mail.theitbros.com internet address = 22.214.171.124
Debug option allows you to obtain additional information contained in the headers of client DNS requests and server responses (lifetime, flags, record types, etc.):