ARP (Address Resolution Protocol) explained

[lagapidis (Lazarus Agapidis)]

Hello Narad

In the scenario that you describe in your post, the gratuitous ARP would be sent by the secondary port of host 1 that has just been enabled. All devices (including host 2) that recieve the gratuitous ARP will update their ARP caches. You can find more information about this process at the following post:

ARP (Address Resolution Protocol) explained

Hello Juan It is true that ARP entries by default are kept in the ARP table for four hours. As you mentioned very correctly, this can be a problem if you install a new PC with the same IP address. Other cases where this could be a problem is if a server has a backup NIC card and the first fails, the backup will have the same IP address but a different MAC address. In order to solve these issues, we use something called a Gratuitous ARP. Gratuitous ARP is a sort of “advance notification”, it…

I hope this has been helpful!

Laz