DHCP Warning Sign Icon On Windows Server

As TomTom says, the solution is to SPLIT the scope not MIRROR it. Please note that this is a very important distinction because for high availibity, you need enough IP addresses in each half of the scope to support all connecting clients.

Server 2008 R2 makes this extra easy for you:

• Open DHCP Management
• Expand everything so you can see each individual scope
• Right click on the scope, goto advanced and select "Split-Scope"

You can then use this wizard to automatically split your scope into two and create it on the other DHCP server.

Since I've had the privilege of actually working in this specific environment, I can say with certainty that the DC that is hosting DHCP fails replication and goes unresponsive to requests for various Directory Services functions (like authorizing DHCP servers) every few weeks. This DHCP issue is a symptom of the larger replication problem.

Since the server that DHCP is on is a DC, it only ever looks to itself for authorization. When Directory Services stops functioning on it, so does DHCP.