If your domain isn't resolving, check the following:
Are your dns names set correctly in your registrar's control panel
If you have incorrectly entered the DNS names in your domain registrar's control panel, this will affect how your domain is resolved.
Your domain is active
If the domain is brand new or recently transferred to your registrar, it can take up to 24 hours for the domain propagation to effect. You can check whether the update was successful by inspecting the WHOIS response for the domain. If after 24 hours the domain is still not resolving, make sure the update was successfully confirmed by your current domain registrar.
Verify with +dig
The +trace setting from dig shows how your domain name is delegated. It runs a recursive query against each of the name servers in the chain, starting from the root name servers.This can be used to debug delegation issues.
$ dig NS example.com +trace
The delegated DNS servers should be the same as ours.