Unusual DHCP activity after power outage

Solution 1:

It is not an answer to your question as I feel there is not enough information to really determine what happened.

To prevent issues with DHCP servers many system administrators prefer to give their servers fixed IP addresses. That being said, I do prefer giving as much devices as possible DHCP leases to have a central database of IP address information.

For laptops a short lease time (e.g. 2-4 hours) is okay. The DHCP client will refresh its lease after half the lease time (i.e. 1-2 hours) which is ideal for people who do not work in the same spot 8 hours. You can also set a longer lease time, e.g. 8 hours.

However, for servers and printers, and in general, any DHCP reservation, you can bump up the lease time greatly as they will never get a different IP address anyway. If you set it to e.g. 30 days, it will ask for a renewal after 15 days and if your DHCP servers remains down for more than 15 days you have bigger problems than your other servers not getting an IP address.