asa transparent and dns problem

[sergiu.campian]

I'm having a strange issue with an ASA 5520 in transparent mode. DNS inspection drops all requests from my internal dns server to the external dns servers. I also have an ASA5520 in routed mode with DNS inspection enabled in the network and dns inspection on that one allows all the packets that the transparent one drops. The software version is the same.

[mirober2]

Hi Sergiu,

If you do a 'clear asp drop' on the transparent ASA and then 'show asp drop' several times, which counters appear to be increasing? There should be some listed related to DNS inspection.

You can also check 'show service-policy inspect dns' and enable 'debug inspect dns error' and 'debug inspect dns event' to see if that offers any insight.

-Mike