ARP table default timeout
The Address Resolution Protocol (ARP) table that is maintained by network hosts keeps ARP entries in the ARP table for several hours. The exact timeout is vendor specific, but Cisco's default timeout is four hours. Juniper on the other hand has a default value of six hours.
Links
https://forum.networklessons.com/t/arp-address-resolution-protocol-explained/864/145?u=lagapides