Shaun is onto a method that might work although it's not foolproof. If you can match a pool member with the virtual server that load balances to it, then check the virtual server's Source Address Translation (SNAT) setting, that may clue you in as to which pool members (servers) have BIG-IP as their default gateway and which don't. I say it's not foolproof for this reason: although a server whose default gateway IS NOT the BIG-IP system must be load balanced to with a virtual server that's using SNAT, it is perfectly acceptable to use SNAT even if the server's default gateway IS the BIG-IP system. So there's no guarantee. (Some F5 customers use SNAT everywhere regardless of the server's default gateway configuration - just in case!)