Before a sub-domain can be delegated, the correct nameserver for the parent domain must be found. In many cases the parent nameserver and the domain registrar are one and the same. Therefore, the registrar’s tools may be used to delegate the sub-domain (see example below). In other cases, the nameserver may be located at a web hosting provider or may be privately operated by your IT department.
Using an Online Tool
A useful tool for nameserver lookup is MX Toolbox (http://mxtoolbox.com/SuperTool.aspx).
- Enter the parent domain name in the “Lookup Anything” box. For example, if the domain to be delegated is “news.example.com”, enter “example.com”.
- Click the down arrow beside the button to the right and choose DNS Check from the menu.
- Click the DNS Check button.
Using a Command-line Tool
For UNIX-based systems such as Linux, the best tool to use is “dig”. Use it to query the name servers of the parent domain, again using “news.example.com” as our delegated sub-domain:
dig +short -t ns example.comFor Windows systems, open a Command Prompt window and use “nslookup”. (It is also possible to use “nslookup” on most UNIX-like systems but it has been deprecated on some in favor of “dig”.)
nslookup -type=ns example.comAdditional detail or to look up several domains:
- In the Command Prompt window, type “nslookup” and press enter. Some information about your local nameserver is displayed and then an “>” prompt appears.
- Type “set querytype=ns” and press enter.
- Type the name of the parent domain, e.g. “example.com” and press enter.
- The name server information for example.com is displayed.
- Enter other parent domains to look up if needed, one at a time.
- Enter “Exit” when you are finished doing lookups.
One the parent domain's nameserver has been identified, continue to the next section to create NS records or, if that is not possible, skip to our documentation on creating a CNAME.