How does Root Servers answers DNS query if you have two GTM?

Hi Earvin,

The DNS Server that requests the NS records from the root servers (as well as next level down, etc), makes a request for all NS records for the domain. The authoritative servers return all relevant NS records for the domain.

It is then up to the DNS server making the final A record request to pick one of the available NS records, and make the query there.

If the NS does not respond, then after the time-out has passed, it queries the next one.

You will find that the Users (computers) themselves will rarely, if ever, have the NS records for your domain since they query either their organisation's DNS Servers, or the ISP. These servers typically recurse on the client's behalf, and are the ones that get the NS records in their cache, and choose on a random/round robin basis (depends on implementation) NS to query.

Typically, the distribution of the requests should be pretty equal across all NS records.

Hope that clarifies things for you a little bit.

Regards,

JohnB