Service Route Configuration - DNS resolution seems to fail

[JohnRoberts]

Hi, 

I'm currently staging a PAN-VM (8.1.3 KVM) and have hit an issue.

The setup:

1. I've configured the interfaces, zones, routing (static default route) etc. correctly.
2. I've modified the service router configuration to use the Internet facing dataplane interface IP (i.e. customized and not use management interface). That is I allow DNS, NTP, Palo Alto updates to access the Internet via dataplane outside/untrust interface. 
3. Under device-->services tab I have entered for DNS server settings (8.8.8.8) primary and 8.8.4.4 (secondary).

The issue:

I commit and immediately after I test pings from the CLI to: 8.8.8.8 sourcing from the outside interface and its sucessfully. I then ping google.com (either continuouly or specifying a ping count of 5) and it works 100%. However, after a few moments issuing new pings to google.com fail and I get the "ping: unknown host google.com". Further, I observe the PAN FW can no longer contact the licensing server or palo alto update server as it relies on successful DNS lookups. I turn my attention back to pings to the IP 8.8.8.8 and it doesn't skip a beat. 100% success.

Any further commits and immediately pings to google.com work again (continuous or count specified ping)  will yield 100% success. However, as soon as I kill the continuous pings (or use count specified ping) and wait a moment, the pings to domain names (google.com) fail again. 

Any ideas?

Cheers,

John

[Chacko42]

@JohnRoberts: Is the issue still persistent?

I would suggest to have a log in the traffic log, if you got any dns response packets, while you experienced the issues.

Nonetheless, the current preferred PAN-OS release is 8.1.8.

If the issue is persitant after upgrading, please test, if other dns resolvers work better for your environment