forward dns queries to sub domain with three name servers

We have a sub domain in our dns tree for a GTM. within the GTM (sub domain ) we have three name servers listed. The question is that is there some kind of time out if the first server in the name server tab does not reply with an answer? From the firewall engineers perspective they are saying that it seems like the DC only tried the third NS in the list? What would cause it to get stuck on on NS(not that i think this is the problem) and how does it decide which record to use and when to switch?
ablsysadminAsked:
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DrDave242Commented:
Do you have a delegation created in the parent domain, and does the delegation record contain entries for all three of the child domain's name servers?

If you're using Windows DNS in the parent domain, a delegation record looks like a gray folder with the name of the child domain. Selecting that folder in the left pane of the DNS console will cause the right pane to display the nameserver records it contains.
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ablsysadminAuthor Commented:
Yup MS DNS in the parent. the child domain(grey) is reflecting the NS server names of the GTM's. We removed the third entry and it seemed to remedy the issue. The question was more around how does DNS decide which NS record to use and if one does not respond what is the timeout before it moves to the next record.
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ablsysadminAuthor Commented:
It seems like the third GTM address was pointing to a GTM with a 'clean' config. So to add to the above questions: If a DNS server forwards the query to a NS in a child domain and does it require an reply message or something. Because if a server comes back to a 'no such host' message would it then jump to the next server in the NS list?
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DrAtomicCommented:
if a server comes back to a 'no such host' message would it then jump to the next server in the NS list?

No, if the server (which is the dns client in this scenario) gets the 'no such host' message then it is receiving a response with 'no such host', another nameserver is only used if the first one that is used isn't reachable (or times out). But in the end it all depends on the local dns client implementation. This article goes into more depth with regards to timeouts: http://blogs.technet.com/b/stdqry/archive/2011/12/15/dns-clients-and-timeouts-part-2.aspx
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