The cache timeout on Palo Alto Networks firewalls is 30-minutes (1800 seconds) for ARP entries on all interfaces, which is a fixed setting and cannot be adjusted. If you do want to clear the ARP manually, you may run a commend line.
- To show arp status, run this command: >show arp all
- To clear arp on ethernet1/1, run these command: >clear arp ethernet1/1
- To clear all arp, run this command: >clear arp all.