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kridsana's avatar
kridsana
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Sep 04, 2018

iRule to resolve DNS for GTM (wide-ip if possible)

Hi

 

I've server on cloud and want to try to use irule to resolve dynamic IP from cloud and return IP to user.

 

I saw irule LTM can use RESOLVE:lookup and we can use it on Listener.

 

But Is it possible to have the same function irule in wide-ip ?

 

because if we attach irule on Listener, it will surely take more performance than wide-ip.

 

Flow is When user send dns request for wide-ip "A" -> F5 resolve dynamic IP from cloud (it's hostname will be like ABCDEFG.cloud-us.com)-> F5 return IP to user.

 

ps. due to some circumstance CNAME is not possible.

 

Thank you

 

  • FYI

    This is irule that can include on Listener. (But not wide ip)

    The irule resolve dynamic IP from AWS and return to user.

    Cloud server is ABC.ap-southeast-1.elb.amazonaws.com
    when DNS_REQUEST {
    if {([string tolower [DNS::question name]] equals "ABC.com") && ([DNS::question type] equals "A")} {
        set aws [RESOLV::lookup @8.8.8.8 -a "ABC.ap-southeast-1.elb.amazonaws.com"]
        DNS::answer insert "[DNS::question name]. 111 [DNS::question class] [DNS::question type] [lindex $aws 0]"
        DNS::return
        }
    }