Weird one... I have never seen this behavior before
Here's what we have 3 x Exchange 2010 (WNLB) CAS Array & 3 x Exchange 2010 MBX Servers in a DAG - all running on wIN 2008 R2 VMWare (ESX5)
All bar 2 servers can communicate... ping, UNC paths etc... so obviously, i have a Public Folder replication issue with these 2 servers.
CAS 3 & MBX will just not "talk" to each other
I changed IP's on the CAS' NIC (updated the WNLB etc..) - no good
I added another vNIC to the CAS server, assigned an IP etc... bingo - can ping/map drives etc... but, alas i cannot add the new NIC to the WNLB CAS Array... Grrr!
I cam across this KB article - but applicable in our case: http://support.microsoft.com/kb/2649727
We are running Exchange 2010 SP3 UR2
Any ideas guys?