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danielpenna's avatar
danielpenna
Icon for Cirrus rankCirrus
Jun 23, 2014

Selective DNS queries

Hi All, I am trying to route DNS queries to authoritative servers based on DNS/Hostname request. I have run up a 11.5.1 host in AWS and trying to figure out the GTM configuration but I think/hope what I want to do can be achieved by a DNS iRule but having issues figuring it out.

What I want to do is something like below, anything in AWS will use the F5 DNS Virtual Server as the default DNS server and when a DNS request comes in for a amazonaws.com DNS name it routes the request by a DNS server with external DNS resolution capability. If a request comes in to F5 DNS VS with a DNS request for an internal AD dns name it gets routed to our internal DNS servers.

Is this possible ? Something similar to the iRule below hopefully...still getting my head around GTM at the moment.

when DNS_REQUEST {

if { [DNS::question name] contains "amazonaws.com" }
{
    pool pool-external-dns
}
else {
        pool-default-internal-dns
}

}

application delivery
BIG-IP DNS
cloud
devops
iRules

3 Replies

  • Kevin_Davies_40's avatar
    Kevin_Davies_40
    Icon for Nacreous rankNacreous
    Jun 23, 2014

    Try the following. The pools you are selecting need to be DNS server pools

    when DNS_REQUEST { 
  if { [DNS::rrname] ends_with "amazonaws.com" } { 
    pool pool-external-dns 
  } else { 
    pool-default-internal-dns
  }
}
  • danielpenna's avatar
    danielpenna
    Icon for Cirrus rankCirrus
    Jun 23, 2014

    I was getting errors with DNS::rrname so have changed it to [DNS::question name], will test and confirm.

     

    Thanks Kevin