Mar 27, 2026 - For details about updated CVE-2025-53521 (BIG-IP APM vulnerability), refer to K000156741.

Forum Discussion

f5user_108265's avatar
f5user_108265
Icon for Nimbostratus rankNimbostratus
Jul 17, 2008

GTM iRule defining external DNS server

Hi everybody,     I am facing the following problem. I would like to force the GTM to query an internal (accessible only by the BIG-IP on the private side) DNS server if the DNS record cann...
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JRahm's avatar
JRahm
Icon for Admin rankAdmin
Jul 21, 2008
The forwarders in the named options section are your name servers, not the zones. You can forward by zone instead of globally. This must be setup in each zone's configuration: 

 
 zone "internal.company.com" in { 
     type forward; 
     masters {ns1.internal.company.com; ns2.internal.company.com}; 
 };

If you're going to be doing much work with DNS, I highly recommend the O'Reilly DNS & BIND book (latest edition)