Forum Discussion

PPawar_309940's avatar
PPawar_309940
Icon for Nimbostratus rankNimbostratus
May 23, 2018

F5 DNS Forwarding

Hi Guys,

 

We have configured F5 DNS as GSLB and not running it as a BIND.

 

We have got some external bind servers configured as standalone servers.

 

Now I want to set up dns forwarding on F5 based on the domain.For example

 

If the request is coming for anything on the domain *.abc.com and if F5 doesn't know about it then it will forward that request to external bind server.In a nutshell

 

  • dns request comes to F5 for *.abc.com, if it finds the match then reply with the answer
  • dns request comes to F5 for *.abc.com, if it doesn't find the match it will forward the request to bind server 10.10.10.10
  • dns request comes to F5 fo5 *.xyz.com, if it finds the match then reply with the answer
  • dns request comes to F5 for *.xyz.com, if it doesn't find the match it will forward the request to bind server 10.10.10.10

And finally for all domains i.e everything else(/) F5 will forward the dns request to different bind server 20.20.20.20

 

Please if anyone could help me with iRULES or with any other approach then it will be appreciated.

 

Thanks, Pan

 

application delivery
BIG-IP DNS
  • Leonardo_Souza's avatar
    Leonardo_Souza
    Icon for Cirrocumulus rankCirrocumulus
    May 23, 2018

    DNS traffic will be handled by BIG-IP DNS listener, that is basically a LTM virtual server. Try to disable BIND in the DNS profile, create a pool with the DNS servers, and add the pool to the listener.

     

    In theory, it should the job you want.

     

  • Jinshu's avatar
    Jinshu
    Icon for Cirrus rankCirrus
    May 24, 2018

    can you test this?

    when DNS_REQUEST { 
 if { ([IP::addr [IP::client_addr] equals 0.0.0.0]) } { 
    switch -glob [string tolower [DNS::rrname]] { 
        "*.abc.com" -
        "*.xyz.com" { 
        pool 10_10_10_10_pool
        } 
        else { 
        pool 20_20_20_20_pool
            } 
        }
    } 
}

    -Jinshu