@jeff - Thank you for posting your question on the forum!
The ARP cache will be flushed with a reboot of an AOS device. You can also flush the ARP cache in the CLI by issuing the clear arp-c command.
The default ARP cache time out is 20 minutes.
You are able to add a static ARP entry to an AOS device in the CLI. The command in config mode is shown below:
switch(config)# arp <IP Address> <MAC Address> arpa
Example: switch(config)# arp 18.104.22.168 aa:bb:cc:dd:ee:ff arpa
I hope this answers your question, but please do not hesitate to let us know if you have any further questions.
@jeff - I went ahead and flagged this post as “Assumed Answered.” If any of the responses on this thread assisted you, please mark them as either Correct or Helpful answers with the applicable buttons. This will make them visible and help other members of the community find solutions more easily. If you still need assistance, I would be more than happy to continue working with you on this - just let me know in a reply.