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smalex_355988's avatar
smalex_355988
Icon for Nimbostratus rankNimbostratus
Apr 23, 2018

DNS Failover Mechanism

Apologize for a very basic question. We have one F5 DNS in DC and one in DR. For our domain abc.com, in the service provider, Authoritative DNS is DC DNS & DR DNS. As per my understanding, ISP would...
application delivery
BIG-IP DNS
youssef1's avatar
youssef1
Icon for Cumulonimbus rankCumulonimbus
Apr 23, 2018

Hello,

 

it's not a basic question. On the contrary, it is important that you raised it

 

I recapitulate. you have 2 dns that are authoritative for your domain abc.com.

 

ns1.mydomain.com

 

ns2.mydomain.com

 

If you F5 DNS Fail (ns1.). it will happen the following way...

 

User will try to join (he will make a request to his ldns). It all depends on how its dns, iterative or recursive is configured suppose it is iterative:

 

  • User request to his ldns

     

  • ldn request Root Hint (.com)

     

  • then ldn request level hint...

     

  • then ldn request ns1.mydomain.com ns1 dont'answer, ldn wait 1 second then try ns2...

     

this timeout is differente between windows and Linux system...but in general it is of the order of a few seconds (1s)...

 

Let me now if it answers your question.

 

Regards