topic Re: DNS Traffic slow/time out after applying Anti Spyware in Advanced Threat Prevention Discussions

DNS Traffic slow/time out after applying Anti Spyware

rjdahav163 — Mon, 21 Dec 2020 01:01:18 GMT

Hi everyone,

We are using PAN OS 9.1.5.

Our internal hosts and DNS server are in different PA Zones.

We have a policy to allow all hosts to access DNS servers with application "dns".

We used strict anti spyware profile on the above mentioned security policy.

After applying anti-spyware profile, we see that the DNS queries timeout most of the times and very rarely when they work, the queries will take a long time.

As soon as we remove the Anti Spyware profile, everything woks normally. I am totally lost and cant find the root cause. Since there are no logs as well!!

Is this any known issue? Does anyone else have similar problem?

Thanks!

Re: DNS Traffic slow/time out after applying Anti Spyware

SutareMayur — Mon, 21 Dec 2020 11:11:07 GMT

Hi @rjdahav163 ,

Did you checked Threat Logs? You can verify threat logs with below filter. Also verify the logging configuration on the security policy.

( subtype eq spyware )

Re: DNS Traffic slow/time out after applying Anti Spyware

MauricioPerez — Tue, 22 Dec 2020 16:54:43 GMT

HI, are you only applying anti-spyware security profile? If so, you could look at the threat logs and additionally check the packet capture configuration, you may have enabled extended captures on criticalities that do not need it.

Re: DNS Traffic slow/time out after applying Anti Spyware

mivaldi — Thu, 24 Dec 2020 22:55:57 GMT

Your DNS Server is likely sourcing multiple DNS queries re-using the same source port. When this happens and a threat is detected, a DISCARD session is installed, and all subsequent queries 'trip' over the DISCARD session.

Re: DNS Traffic slow/time out after applying Anti Spyware

ramakrishnan.v05 — Mon, 25 Aug 2025 18:09:39 GMT

I too having same issue, what was the fix @rjdahav163 ? while applying Security profile (particularly Anti-Spyware) DNS intermittently working, most of the time its stopped working as then removed the security profile its started working. What would be the root cause. Actual challenge here is we cannot reproduce the issue as it impacting the production. Neither getting downtime also nearly impossible. Any quick solution or insights/findings much appreciated.

Re: DNS Traffic slow/time out after applying Anti Spyware

ramakrishnan.v05 — Mon, 25 Aug 2025 18:10:02 GMT

I too having same issue, while applying Security profile (particularly Anti-Spyware) DNS intermittently working, most of the time its stopped working as then removed the security profile its started working. What would be the root cause. Actual challenge here is we cannot reproduce the issue as it impacting the production. Neither getting downtime also nearly impossible. Any quick solution or insights/findings much appreciated.