Querying a network::dns resolver from an Irule ?

Hi ! Previously I was making DNS requests from an irule using the RESOLV::lookup function, directed towards a VS containing several external DNS servers. This works great. Recently on the same bigip I created a "DNS Resolver" (GUI Network::DNS Resolvers) to use with an HTTP forward proxy VS. This is very useful and allowed me to configure the same remote DNS servers ("." zone). This is working great as well. However, now, to optimize the working of my BigIP and "share" the caching between my irule and the forward proxy, I wonder if it is possible to resolv to the proper "DNS resolver" from the irule. I had no chance using the RESOLV::lookup function, as it seems to work only with a real VS. Any clue anybody ? Thank you very much in advance :-) PS : I use 11.5.1 with LTM module enabled.