I have been searching for a few answer that i can not seem to find answers to. I'm hoping someone can help me out with my three questions. I have been looking at forum post and i seem to get a lot of conflicting info or maybe i'm not searching for the write terms but any help would be great. Setup: I currently have 4 existing Exchange 2007 servers. 2 CAS/HUB servers and 2 Mailbox servers in CCR. We are moving to Exchange 2010, so i have built 4 new servers. 2 CAS/HUB and 2 Mailbox servers using DAG. I have the exch2010 CAS/HUB servers setup using Network Load Balancer for OWA balancing. Question 1: I want to create the CAS array but do i need to create the CAS array with new IPs and DNS name or can it be setup to use the existing NLB setup with the same DNS name? Question 2: If i do create the CAS Array will it ignore my two existing 2007 CAS servers? Question 3: Do i need to have a DNS entry for addressing the DAG?

Hey mate, You will need to install with new server names, IP, DNS and NLB if you want co-existence Once you change over your SMTP and web services you will no longer need the old CAS/HT servers When you create the DAG it will create a Computer object in AD for the DAG and register it in DNS automatically Matt Cline - MCSE+M, MCITP: EA | EMA (2007, 2010) | Lync 2010 Blog: exchangeadventures.wordpress.com

1. just cause i wasn't clear above, the NLB is only setup on the Exch2010 CAS/HUB. The exchange 2007 CAS/HUB have no NLB setup on them. Take it the answer is still the same? 2. so i can not create the CAS array until i have removed the Exch2007 CAS servers?

You can create a new array for the Exchange 2010 CAS/HT servers as part of the initial build before migrating users to the Exchange 2010 system, it will not affect the Exchange 2007 environment at all. And yes point 1 does not change :)Matt Cline - MCSE+M, MCITP: EA | EMA (2007, 2010) | Lync 2010 Blog: exchangeadventures.wordpress.com

OK last question about CAS Array setup. So when I issue the "Get-ClientAccessServer" from Exchange 2010's management shell, i see that it has the exch 2007 CAS servers as well as the Exch 2010. If I issue the "New-ClientAccessArray" command won't it try to include the two Exch2007 CAS servers? I'm still learning powershell right now so I could be completely missing the command that lets me specify the exact servers to include. I have also read alot of how-tos on creating a CAS array for 2010 but non seem to address creating the array when the current 2007 servers are still running.