Exchange 2003/2010 coexistence questions
Posted on 2011-03-17
We are running an Internet-facing Exchange 2003 SP2 on a Windows 2003 DC. We also have 2 new DCs running Windows 2008. We are planning on installing all Exchange 2010 roles on one of the new 2008 DC and run a coexistence environment for a few weeks. Our Exchange 2003 server name is server.contoso.internal. Our users run a mix of Outlook 2003 and Outlook 2010. Outlook is configured to connect to server.contoso.internal when on LAN and mail.contoso.com for Outlook Anywhere. Our internal DNS servers host 2 zones: contoso.com and contoso.internal. Both zones have A records for server.contoso.internal and mail.contoso.com pointing to the internal IP address of the Exchange 2003 server. The external DNS servers also have an A record for mail.contoso.com pointing to the public IP address of our Exchange 2003 server.
As I understand, in a coexistence environment, all clients will be connecting to the CAS 2010 first and be directed to the Exchange 2003 when the mailbox has not yet been migrated. I reviewed Microsoft's papers explaining the configuration of /externalCASSeverDomain, LegacyRoutingServer, OWAVirtualDirectory and installation the new SAN certificate. My questions are:
- How will Outlook clients know how to contact the new CAS2010 server when on the LAN? They are currently pointing to server.contoso.internal. Because server.contoso.internal is a DC, I cannot update the IP address of the A record and point it to the CAS2010 server. I also cannot rename the server from server.contoso.internal to legacy.contoso.internal. What am I missing?
- Although all servers are members of the domain, the clients are not. Their local credentials match the domain user credentials so authentication has been transparent with Exchange 2003. Any concern with Exchange 2010?
- We use a large number of address lists. I'd like to confirm we need to migrate the address lists before any mailbox is migrated for all users to have access to them.
- As I understand, the hub transport role is necessary for email to flow between 2003 and 2010. Does the installation of the hub transport role mean all Internet traffic has to flow through Exchange 2010 from that point on?
Thank you for your help.