How to Configure and Test FQDN Objects

• PAN-OS 7.1 and higher.
• Palo Alto Firewall.
• Address Object Configuration.

Considerations

• The FQDN object is an address object, which means it's as good as referencing a Source Address or Destination Address in a security policy.
• Therefore, every 30 minutes, the Palo Alto Networks Firewall will do an FQDN Refresh, in which it does an NS lookup to the DNS server that's configured (Setup > Services). The firewall maps up to 32 IP addresses to that FQDN object.
• Make sure that this is the same server that your hosts are using. DNS malware can adversely affect a solution like this.
• Use this method only when using an IP address is not possible--don't use this type of object as part of a URL filtering policy.
• This can also be helpful to control other services that don’t relate to web browsing like ftp, ssh, or any other service.
• If the object also resolves to an IPv6 address, enable IPv6 Firewalling (Device > Setup > Session).

Configuring the object

To begin configuration of FQDN objects, go to Objects > Addresses

1. Click Add to create a new address object
2. Change the type from ‘IP/Netmask’ to ‘FQDN’
3. Enter the address (do not include http:// or any other header)
4. Click OK
5. Commit the changes

On the CLI, FQDN objects can be set using the following command in configure mode:

# set address Google fqdn www.google.com

Confirming the changes

• An automatic Refresh FQDN task will run in the background. The status of this job can be checked by clicking the Tasks button at the bottom right corner of the GUI.
• The CLI command below can then be used to view the list of FQDN objects and the IP addresses associated with that name.
  • PAN-OS 8.1 and below: > request system fqdn show
  • PAN-OS 9.1 and above: > show dns-proxy fqdn all
• It is possible to force a refresh by running the command above.
• As a recommended extra check, ping the host from a desktop to make sure it matches the IP address listed after running the command.