BigIP GTM/DNS - no listener?

May be the Bind server is responding to any DNS request instead of GTM.

to make it work, the Bind option

listen-on port 53 { 127.0.0.1; };

GTM, like all others BigIP products requires a "listener" object to handle traffic.

This listener object is a Virtual server with specific properties.

A GTM listener create a Virtual server listening on port 53 (tcp or udp) with a dns profile.