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AlanStrange_168's avatar
AlanStrange_168
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Mar 08, 2019

GTM DNS Wide-IP-Pool-Irule Question

Hi, First time poster here. We've got an issue where, with a GTM, we had 1 x WideIP with 2 x CNAME pools sitting behind it. There was also an iRule attached to the WideIP which queried the Active Members in those pools as part of its logic, so as to select the correct Pool. All was working fine.

 

We've since upgraded from 11.5 -> 12 and a few things have happened :- - our 1 x WideIP has been split into three(A, AAAA, CNAME) - the existing irule has been added to the CNAME WideIP - both CNAME pools have been added to the "A" WIP

 

As we only ever receive "A" record requests, this causes us a problem as our irule functionality is never triggered. We get a CNAME being returned, as the CNAME records are now sitting under the "A" WideIP, but no irule logic takes place.

 

We've tried adding the irule to the "A" WIP, but as we are adding it to an "A" WIP, when we reference a pool in the irule, it is expecting an "A" Pool...which we don't have. Consequently, it won't let us add it. Creating an "A" Pool, allows us to add the irule, but then only ever returns the IP address in the Pool.....whereas we need the CNAME from the CNAME pools.

 

Does anyone know of a way to reference a CNAME pool from within an iRule...or indeed any way round this issue.

 

Thanks.

 

Alan.

 

  • I would check your configuration of the CNAME WIPs. If you don't need an A record WIP and the requests can be made for CNAMEs, then it might be beneficial to just have a CNAME WIP and no A record WIP. If you must have an A record WIP, you could simply add an iRule on the A record WIP that selects which requests should be sent as a CNAME with the cname command.

     

    If you have any questions or need more help, I am sure I can help.