BIG-IP DNS Forwarder Support via iRule

Problem this snippet solves:

The BIG-IP DNS Product does not currently (without named) support DNS forwarders. Some customers wish to avoid exposing named but want forwarder support.

How to use this snippet:

Apply this iRule to your BIG-IP DNS Listener and configure a datagroup

Code :

when DNS_REQUEST {
    set forwarded 0
    if {[class match [DNS::question name] ends_with forwarded_zones]}{
        set count [table incr [class match -element [DNS::question name] ends_with forwarded_zones]]
        log "Count for [class match -element [DNS::question name] ends_with forwarded_zones]]: $count"
        DNS::disable dns-express cache bind gtm
        set forwarders [class match -value [DNS::question name] ends_with forwarded_zones]
        log "Query question: [DNS::question name] Type: [DNS::question type] - Forwarders: $forwarders"
        set forwarder_list [split $forwarders]
        set forwarder [lindex $forwarder_list [expr $count % [llength $forwarder_list]]]
        log "Forwarder: $forwarder"
        translate address enable
        snat automap
        node $forwarder
    }
}

Tested this on version: