Public DNS Resolvers (and using dig)

A while ago I move most of my domains from using the DNS servers of Godaddy to my own DNS servers. Every time I'd move a domain, Godaddy would drop it from their DNS server immediately but the world would pick up the change on latest.

Sometimes even more than 48 hours later.

More specifically, if I understand this correctly, what takes time is the update of all the global root servers that should know where is the DNS server of the domain.

As far as I understand there are two solutions to this:

  1. the old DNS provider should keep the dns records for at least 2 days after I officially stopped using them.
  2. Have 2 steps:
    1. Add the new DNS resolvers to configuration of the domain and have the new resolvers already work.
    2. After all the root servers already know about the new resolvers, remove the old ones

Unfortunately Godaddy stopped supporting these. Luckily almost all of my domains are already using my own DNS servers.

Tools to check resolution (Global DNS propagation)

I found / was recommended two sites that can help me see how the rest of the world sees the DNS records of a particular domain:

What's my DNS

Open DNS cache

dig is the ultimate Linux command line tool for DNS lookup

List all the name servers


   $ dig +nocmd . NS +noall +answer +additional

I think I knew how to check what the root name servers think about the DNS server of a particular domain, but now I don't remember


   $ dig @k.root-servers.net  perlmaven.com NS +short +trace

Seems to work (checking the k root server), but I am not sure if that's the best way to do it.

And just in case I forget, this is how I can list the records of mail.perlmaven.com as known by ns.tracert.com


   $ dig mail.perlmaven.com @ns.tracert.com



Published on 2013-07-11 by Gabor Szabo

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