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Question with DNS Query

Posted on 2004-09-24
Last Modified: 2010-04-17

What do A.GTLD-SERVERS.net, B.GTLD-SERVERS.net, ..., I.GTLD-SERVERS.net mean in DNS query? Thanks.
Question by:yeshengl
  • 2
  • 2

Expert Comment

ID: 12147921
These are the actual DNS servers, where A.GTLD-SERVERS.net is the first, and B.GTLD-SERVERS.net is the second backup server, etc...  There are backups so that when one goes down, your whole domain does not go down because it could be resolved in another backup sever.

Expert Comment

ID: 12154420

Those are the "Global Top Level Domain" Servers (GTLD..)...
I can't give you more information because I don't know the query you made to get that...


Author Comment

ID: 12156566
Thanks. I am trying to query DNS with socket programming. Do you know how to do that?

Accepted Solution

sowyn earned 50 total points
ID: 12157951
Ok, I think you have to change the DNS server: you should set it to the nameserver which hosts the domain you are querying.

For example, if I query the domain libero.it in the server a.gtld-servers.net I get:

(root)  nameserver = g.root-servers.net
(root)  nameserver = f.root-servers.net
(root)  nameserver = a.root-servers.net

and their reverse:

g.root-servers.net      internet address =
f.root-servers.net      internet address =
a.root-servers.net      internet address =

But if I change the DNS server and try to set the server which maintainces that domain (, it gives me the full information about it:

        primary name server = ns1.libero.it
        responsible mail addr = hostmaster.iol.it
        serial  = 2004091500
        refresh = 86400 (1 day)
        retry   = 1800 (30 mins)
        expire  = 604800 (7 days)
        default TTL = 86400 (1 day)

and so on...

Author Comment

ID: 12223576

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