Our experiences with migration from windows 2003 R2 to Windows 2008 R2 Domain&Forest

[bio]

Last week we migrated our domain/forest from windows 2003 R2 to Windows 2008 R2. I thought i share my experiences with you guys.

DFS
We had some issues with creating DFS domain namespaces. It seems that after installation we could create a windows 2008 namespace type. The enable windows 2008 mode was greyed out. Solved this by rebooting every domain controller that was used to hold the domain namespace.

The second issue we had with DFS is that we could not create new DFS namespaces since there we still old DFS namespaces residing in active directory. To resolve this issue I found this article
DFS Namespace Management: The namespace cannot be queried. The RPC server is unavailable. - Ivan Lu?i? - my blog

DHCP
We needed to migrate our DHCP servers from windows R2 to Windows 2008 R2 as well.
We did this by using the netsh dhcp server export and import commands. DO NOT use these commands to migrate your DHCP Server. We had serious problems since it didn’t migrate our reservations well and ended up with a corrupt DHCP Database. I also read various threads across the net that said the same. Use the following procedure to migrate it :
DHCP Migration

There is another issue I found with a Windows 2008 R2 DHCP that is not documented. It is not possible to create a reservation anymore in a scope that holds an ip address that is not used in that scope. For instance you have a scope from 10.10.10.1 to 10.10.10.100 and you want to create a reservation for a PC that needs IP 10.10.10.101. You get a nice error warning that this is not possible. Quite annoying for us since it was supported on a Windows 2003 R2 DHCP Server.

DNS WPAD
We have an ISA 2006 in our environment and after we migrated our domain to Windows 2008 R2 all PC’s that had an ISA Firewall Client could not connect anymore to that ISA Server.
We got a warning : Could not detect ISA Server.
After investigation this we found out that Windows 2008 R2 DNS Services had a new feature called DNS Block list. The wpad entry was blocked by default so that was the reason that the Firewall client could not connect. You must remove the wpad entry from that block list.
Removing WPAD from DNS block list
About implementing WPAD

Hope this helps people out there.
Bio…

[rvdmast]

Thanks, now that we know we can be prepared for these issues.
As for the DNS/WPAD issue, i think we had that same issue when
we introduced our first 2008 (not R2) server. So that's already covered.

[Davit2005]

Partially upgraded Domain over summer hols

I have raised the schema to 2008 R2 and set up one 2008 r2 server but still have a 2003 DC. We have certain issues trying to manage the 2003 DNS from the 2008 DNS management console but everything else ok. We also a few get bogus error messages from the 2008 server when running DCDIAG but these are normall given our setup as we can't install RODC's anyway till all DC's are running 2008.

I think the DHCP limitation setting the reservations within the scope makes sense, feasibly how could you distribute an IP address outside the scope of IP address distribution. I normally set the scope for the whole of the IP range then just exclude ranges for static addresses and then setup reservations within scope if needed. It is also poss to setup a range of addresses within the scope such as those which maybe assigned to staff devices that need special proxy/firewall treatment but you don't want to give a static IP to but need to give reservations to so they get a fixed IP.

[rbance]

We started over again....had minimal issues...new domain on 2008R2.

Been through this process a few times and the pain is not worth it....plus a proper design and starting again gets rid of a lot of legacy issues.....

[edutech4schools]

DHCP
We needed to migrate our DHCP servers from windows R2 to Windows 2008 R2 as well.
We did this by using the netsh dhcp server export and import commands. DO NOT use these commands to migrate your DHCP Server. We had serious problems since it didn’t migrate our reservations well and ended up with a corrupt DHCP Database. I also read various threads across the net that said the same. Use the following procedure to migrate it :
DHCP Migration

Not sure why you had issues as I use this method almost weekly.