# Migrating DHCP scopes.



## peter79 (Dec 17, 2010)

Guys I need some advice.

I currently have 2 domains with full trust relationships between them. Domain 1 has DHCP running on its 2003 DC. I have a DHCP cluster (Win 2008 R2) in domain 2. Each scope on the DHCP server is in a differenrt vlan and the network device between domains has a DHCP helper address configured for each vlan.

The plan is to migrage the scopes to domain 2 and change the helper address for each vlan pointing to the new DHCP cluster. I picked a small test vlan first. 

On the test scope the lease duration was set to 8 days but it was changed to 1 day. However we wanted to make sure that the current leases were all set to expire after a day and not 8 so a day before the change we deleted the old leases.

The following day the scope had registered new leases with an expireation period of 1 day. I changed the DHCP helper address to point to the new DHCP cluster (the scope was all ready configured and active). 

An hour or 2 after the change over I started seeing bad addresses on the DHCP cluster and 2 users reported IP conflicts. At this stage I still had the scope in domain 1 active so I deatciaved the old scope.

I'm not sure what happened. The leases on the scope 1 in domain 1 were due to epire the following morning so I thought that when the clients went to renew their addresses they would simply go to the new DHCP cluster in domain 2.

My apologies for the long rambling post but if anyone has any comments or thoughts on this it would be greatly appreciated. I have a lot more scopes to migrate and I want to avoid the same problems again.

Thanks.


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