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David__Pasch's avatar
David__Pasch
Icon for Altostratus rankAltostratus
Jun 02, 2017

Big-Ip DNS - Topology LBing and Return-to-DNS

DevCentral, I absence of a lab to test this, I am posting this question to you. If I have a WIP set up for topology load balancing, with three pools. topo records for:

 

region 1 to pool 1 score 20

 

region 2 to pool 2 score 20

 

unmapped to pool 3 score 20

 

If return-to-dns is ONLY set on pool 3, will the other pools also return-to-dns? OR Will I need to create lower cost topology mappings for region 1 and 2 to go to pool 3, so they can use the Return-to-DNS feature?

 

Like:

 

region 1 to pool 1 score 20

 

region 2 to pool 2 score 20

 

unmapped to pool 3 score 20

 

region 1 to pool 3 score 10

 

region 2 to pool 3 score 10

 

Thanks in advance!!!

 

application delivery
BIG-IP DNS

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  • Leonardo_Souza's avatar
    Leonardo_Souza
    Icon for Cirrocumulus rankCirrocumulus
    Jun 02, 2017

    Forget the topology part for a few seconds.

     

    If you had global availability, so pool1 -> pool2 -> pool3 (with return to DNS). If pool1 can't handle the request, the GTM will go for pool2 and not bind. However, if you have return to DNS in pool1, it will go to bind, so never reaches pool2.

     

    Now back to topology...

     

    If you say to send traffic to pool1 only, and that pool can't handle the traffic, it will not send to pool3. To do that, you have to play with the topology score, and have a record to pool1 and one to pool3.

     

    There is also the last resource pool, but that is more for when everything is down.

     

    https://support.f5.com/csp/article/K15258