How to get authoritative answers from nslookup? [closed]

Solution 1:

You should have a look at how DNS works: http://en.wikipedia.org/wiki/Domain_Name_System.

Every domain is managed by authoritative name servers, and Yahoo server are not the authoritative ones for the stackoverflow.com domain; what's happening here is, when you ask them for info about a domain they are not authoritative for, they in turn ask the authoritative servers, and return their answer to you; thus, the answer you get for your query is non authoritative, because Yahoo's DNS servers are only relaying it to you from other servers, they are not the ones which actually manage that domain.

In order to find the authoritative name servers for a domain, you should perform a NS query:

> set query=ns
> stackoverflow.com

stackoverflow.com       nameserver = cf-dns02.stackoverflow.com
stackoverflow.com       nameserver = cf-dns01.stackoverflow.com

If you ask one of those servers, you'll get an authoritative answer.