I recently had an unrelated network outage where we had to take the DHCP server offline for a few hours and had an interesting thing happen. As soon as the server was shut down all f my DHCP registered phones said "IP Address Released" and then would not come back up until the DHCP server was back online. Intersetingly also, there was one live voice conversation going when this happened it that call stayed up until the phone was hung up and then it too released it's IP and no longer functioned.
All of the leases and then been renewed for time lasting well past this planned outage. I am wondering if this is because of some keepalive failing? If so what keepalive would it be and how would I prevent this from being a problem again?
Thanks for any asistance.