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Amit585731's avatar
Amit585731
Icon for Nimbostratus rankNimbostratus
Nov 10, 2016

DNS lookup for ltm

Hi All,

 

Needed help on one of the issue where user has asked us to create outbound VIP for one of Akamai application. Since Akamai is CDN based so IP keeps on changing and I can't add static IP, also since the version we are using 11.4 so I can't use DNS populate option (which is available in 11.6). The req is

 

user -> DMZ -> firewall -> Akamai server

 

Since this LB is in DMZ we are not allowed to add DNS option (which is available under system option). Anyone have implemented this solution or this is not possible?

 

Thanks

 

application delivery
BIG-IP
irule

1 Reply

  • Niels_van_Sluis's avatar
    Niels_van_Sluis
    Icon for MVP rankMVP
    Nov 12, 2016

    Not sure if I understand you correctly, but maybe the irule example in the wiki for RESOLV::lookup could help you.

    when CLIENT_ACCEPTED {

    Get IP(s) for hostname www.example.com against 8.8.8.8 name server
   set dnslookup "8.8.8.8"
   set ips [RESOLV::lookup @$dnslookup -a "www.example.com"]

    Log result. If there are multiple IP's it could be a TCL list like {1.1.1.1 2.2.2.2 3.3.3.3}.
   log local0. "Looked up www.example.com and found $ips, parsed first element: [lindex $ips 0]"

    Check if the first list element was empty
   if {$ips eq ""}{
       Input wasn't an IP address, take some default action?
   } else {
       Select the IP 
      node [lindex $ips 0]
   }
}