GTM iRule - answering DNS based on some criteria.

Thanks Brad.

At the moment I have one pool per wide IP which contains one server from DC1 and one server from DC2, with global fail-over as LB method so it's something similar to your suggestion. This works fine for one client, but I need to have a separate monitor for every single client. I don't want to re-direct all my MPLS and VPN clients if only one line fails. The idea is for GTM in DC2 to response with DC1 wide IP only, if the primary line (to DC1) fails. The problem is related to Linux BIND forwarder which does round-robin instead of global fail-over.

I hope that make more sense now.

Is it possible to refer to a monitor status in iRule?

So far I have the following:

when DNS_REQUEST 
 if { [IP::addr [IP::client_addr] equals 10.1.10.136/29] or [IP::addr [IP::client_addr] equals 10.10.10.64/27] or [IP::addr [IP::client_addr] equals 10.1.10.96/28] } {
      if {monitor status which pings client IP is up } {
        host 1.1.1.1
        else
        host 1.1.1.2

So I am just trying to find the missing function.