1

Good day everyone,

I’m planning DC migration from 2003 to 2008. DC also a DNS server. DC is the only DC in the forest.

My plan is to add secondary DC on 2008 R2, run both for some time. The demote 2003 and add another 2008 as secondary DC with same IP as old 2003.

My question re DHCP server.

While i’ll be running 2003 DC and 2008 alongside i thought of splitting DHCP scopes between two servers. This way reservations and leases are migrated to a new DHCP.

My question is:

Once i shut down 2003 DHCP what changes need to be done on 2008:

  1. Address pool - remove split-scope exclusion

  2. anything else?

Thanks in advance.

T.

2 Spice ups
2

If you use the netsh dhcp export/import commands you can migrate your entire dhcp server at once. I believe it will include the leases and reservations. Just need to, after verifying the transfer of settings, disable the scope on the old server and enable it on the new server.

3

hi cduff, i’ve been reading on netsh dhcp export/import and most comments say it does not migrate reservations. I do not care much about leases but reservations need to be migrated across.

4

Check these out

https://support.microsoft.com/en-us/kb/962355

5

Be sure to unauthorize the DHCP server as well. I typically change the lease times to 10 minutes on the old server, export everything and import it on the new server. Disable the older server and remove the authorization, start the new one and authorize it. Clients should start coming in pretty quickly.

see this as well:

http://community.spiceworks.com/how_to/50877-how-to-copy-dhcp-reservations-from-one-server-to-another

6

If you’re running any CISCO equipment might want to check if there is an IP helper-address set

7

Thank you guys for the info. I’ll have to read thru it first. But still why not to split scope and then delete exclusion from pool?

AdamK_37 - very good point actually. Thanks.

8

I don’t see why the split scope wouldn’t work. Two things come to mind to think about.

  1. check the DHCP response delay after you disable the scope on the old server, as it could have put a delay on the new server that you don’t want.

and 2) there is a potential for IP conflict

Say the servers coexist and the old server issues a lease, then you disable the scope on the old server and remove the exclusions on the new one. Then the new server could reissue that lease. So you’d have to plan to make sure that didn’t happen, by reducing the lease, or restarting all the clients when you deleted the exclusions, or enabling ip conflict detection on the new server, or something else.

9

Well I’ve tested three migration methods:

  1. Split-Scope - is a better option if you have multiple scopes and don’t what to do it all in one go. Less steps overall. As cduff mentioned - pay attention DHCP lease duration.

  2. Server migration tool Export/Import (based on Microsoft Learn Community Content | Microsoft Learn…) Failed on first try with -users All switch, but worked fine without -Users switch.

  3. Netsh export/import - very straight forward, imports all records including reservations (based on https://support.microsoft.com/en-us/kb/962355 )

I’d go with Netsh or Split-scope methods.

Thanks to all for your input.