Best Practices for patching Exchange 2010 servers.

Question

Hi Team,
Looking for best practices on patching Exchnage Server 2010.
Like precautions  , steps and pre and post patching checks.
Thanks. 

Answer 1

Are you referring to Exchange updates? If so:
http://technet.microsoft.com/en-us/library/ff637981.aspx
Install the Latest Update Rollup for Exchange 2010
http://technet.microsoft.com/en-us/library/ee861125.aspx
Installing Update Rollups on Database Availability Group Members
Key points:
Apply in role order
CAS, HUB, UM, MBX
If you have CAS roles in an array/load-balanced, they should all have the same SP/RU level.  so coordinate the Exchange updates and add/remove nodes as needed so you do not run for an extended time with different Exchange levels in the same array.
All the DAG nodes should be at the same rollup/SP level as well. See the above link on how to accomplish that.
If you are referring to Windows Updates, then I typically follow the same install pattern:
CAS, HUB, UM, MBX
With windows updates however, I tend not to worry about suspending activation on the DAG members rather simply move the active mailbox copies, apply the update and reboot if necessary.