Microsoft recommends adopting a software update strategy that ensures all software follows N to N-1 policy, where N is a service pack, update rollup, cumulative update, maintenance release, or whatever terminology is used by the software vendor. Microsoft strongly recommend that our customers also adopt a similar strategy with respect to hardware firmware and drivers ensuring that network cards, BIOS, and storage controllers/interfaces are kept up to date.
Software patching is not simply an issue for Microsoft software. You must also ensure that all inter-dependent solutions (e.g., Blackberry Enterprise Server, backup software, etc.) are kept up-to-date for a specific release as this ensures optimal reliability and compatibility.
Customers must also follow the software vendor’s Software Lifecycle and appropriately plan on upgrading to a supported version in the event that support for a specific version is about to expire or is already out of support.
For Exchange 2010, this means having all servers deployed with Service Pack 3 and either Rollup 7 or Rollup 8 (at the time of this writing). For Exchange 2013, this means having all servers deployed with Cumulative Update 6 or Cumulative Update 7 (at the time of this writing).
For environments that have a hybrid configuration with Office 365, the servers participating in the hybrid configuration must be running the latest version (e.g., Exchange 2010 SP3 RU8 or Exchange 2013 CU7) or the prior version (e.g., Exchange 2010 SP3 RU7 or Exchange 2013 CU6) in order to maintain and ensure compatibility with Office 365. There are some required dependencies for hybrid deployments, so it’s even more critical you keep your software up to date if you choose to go hybrid.