For the second or third time now our dhcp server forgot parts of its reservations and made up random MAC addresses. Why?
We have 2 dhcp servers in failover mode. Everything worked well for years. But now out of the blue after installing some windows updates (and rebooting) the primary server is randomizing the reservations.
New computers are automatically assigned to an IP in a separate network without access to the production and the Internet. For our production network the devices need a reservation. Those reservations are luckily documented in an excel sheet. However, some (not all) reservations magically changed in the dhcp, and nobody knows why.
Last week I learned that the reservations are not replicated to the failover automatically and that there is a button to replicate Failover scopes (I’m going to make a job to execute Invoke-DhcpServer4FailoverReplication daily.)
However, some of the entries where never correct. E.g., there is a VM we created about a year ago and a Notebook that was bought 2013 (!). The reservation changed while they still have the same MAC as in the excel sheet (and Hardware documentation), but a hundred other devices in between still have the correct MAC. Other entries vanished or where replaced. An iPhone was listed with a MAC of 14 digits ?!
The slave server can’t be the source of these entries. On one hand the Notebook is older than the failover server itself, on the other hand the entry for the VM was added this year. If the master somehow replicated the slave, it would have the correct MAC for the old notebook and wouldn’t have the VM at all.
Has anybody an idea how to identify if there is another source for these entries, that the master is somehow replicating?
