Hello all Am in the process of transition from exchange 2003 to exchange 2010 and there will be a co-existence for about one month before decommission the old exchange servers , but something i didn't understand till now, the legacy.domain.com URL must be pointing to the FE exchange 2003, this record should be in our internal DNS or External or Both?, and if it in our external dns i only have one public IP should i have another one. ( i have hardware based firewall not ISA) thanks in advance.

Yes, you need another IP....Gulab | MCTS-MCITP Messaging: 2010 | MCTS-MCITP Messaging: 2007 | MCC 2011 | Skype: Gulab.Mallah

It should be in both Internal and External, assuming internal users who enter "legacy.domain.com" will be able to resolve the name. Only one legacy 2003 URL can exist, so internally if you are "domain.local", the redirect won't work because it will be pointing to "domain.com". This is also assuming internal users use OWA at all. Yes, You need another IP, as legacy.domain.com needs to point to your 2003 FE. When 2003 users try to go to the 2007/2010 CAS, it will just redirect them to the new address "legacy.domain.com" which has to be routable in public DNS. This explains it more in depth. http://blogs.technet.com/b/exchange/archive/2009/11/20/3408856.aspx http://jaworskiblog.com

thanks Scott for the info and the link, it really helped me a lot.