Query regarding NS record

[Kevin Oberman]

On Fri, Sep 16, 2011 at 8:52 AM, Florian CROUZAT
<gentoo at floriancrouzat.net> wrote:
> babu dheen wrote on 2011-09-16:
>
>> Hi,
>>     Can anyone let me know how i can resolve the below requirement.
>>
>> Requirement:
>>
>> We have two offices. One is main office and another one is remote
>> branch office. Now my company client requirement is that if main office
>> DNS server is not reachable, all DNS query should be sent to branch
>> office DNS server. How this can be acheived using BIND?
>>
>> For example, my company mail website is; mail.mycompany.com which is
>> pointed as below in ISP name server.
>>
>> mail.mycompany.com        IN    NS    ns1.mainoffice.com
>> mail.mycompany.com        IN    NS    ns1.branceoffice.com
>>
>>   Is the above record is correct or not?
>>  Please suggest.
>> Regards
>> papdheen M
>>
>>
>>
>>
>
> Babu,
>
> Your example isn't failover, this is load balancing.
> That's two different concepts.

Actually, I would not describe it as either fail-over or load
balancing. It's probably closer to fail-over or the people at the man
office, but not for those at the branch.

I believe that when multiple NS records are available, BIND will
direct queries to the fastest responding server. It does not
"round-robin" queries or anything like that. So, people at the main
office will usually get response from that system and people at the
branch office will usually get responses from that server. But, if the
servers are configured properly, they will always be in sync withing
seconds of any change.
-- 
R. Kevin Oberman, Network Engineer - Retired
E-mail: kob6558 at gmail.com