Question on resolving domain with multiple NS records

robertwessel2 at yahoo.com robertwessel2 at yahoo.com
Wed Dec 21 05:30:27 UTC 2005


Joe Shen wrote:
> Hi,
>
>
> If a domain name has multiple NS records, which NS
> record will be used when a cache server is trying to
> resolve a name in domain?
>
>
> e.g.
>
> I'm trying to resolve domain name www.zjedu.gov.cn,
> and I found there is two NS records for that domain
>
>    zjedu.gov.cn     21600     IN NS   dns.zjedu.org
>    zjedu.gov.cn     21600     IN NS   dns1.zjedu.org
>
> Which NS will be used in further recursive lookup
> procedure?


Most resolvers will just use the first one returned, and switch to the
second one only if they get no response from the first.  Note that the
name server returning those two NS records will typically rotate them,
so if you query it several times you'll get them back in both orders,
and the load from multiple users will end up spread between the two
name servers.



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