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amritkp789's avatar
amritkp789
Icon for Nimbostratus rankNimbostratus
Oct 13, 2017

port based DNS response from GTM

Is it possible for GTM to respond to the DNS queries based on the port that I am trying to access? Elaboration: A FQDN abc.example.com has got two services running one on port X and the other on port Y. VIP for FQDN with port X is configured in LTM A and VIP for FQDN with port Y is configured in LTM B. Now, how does my GTM respond with VIP IP address in LTM A for 'abc.example.com:X' query and with VIP IP address in LTM B for 'abc.example.com:Y' query?

 

application delivery
BIG-IP DNS
dns
iRules

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  • Kevin_Davies's avatar
    Kevin_Davies
    Icon for MVP rankMVP
    Oct 13, 2017

    The short answer to your question is no.

     

    GTM operates at layer 3. The client makes a DNS request to lookup the IP address of the service. This is where GTM is used. The client has not even tried to connect to any service yet as that happens AFTER the IP address lookup is complete which means GTM is no longer involved as the client now talks to LTM.