Repeat the following steps for all 4 DNS listeners.
Navigate to: DNS ›› Delivery : Listeners : Listener List
Navigate to the listener DC01_udp_virtual
Navigate to iRules section
Navigate to Manage
Highlight DNS-query-filtering iRule and move it to Selected column
TMSH commands for router01.branch01
TMSH
tmsh modify gtm listener all rules { DNS-query-filtering }