What is the difference between the Windows Online and Offline Patch Scan? Which one is the preferred method?

The windows online patch scan option finds the missing Microsoft updates at the end points by comparing against central repository hosted by Microsoft called Windows update catalog and for this internet should be prerequisite at the end points.
Windows offline patch scan option finds missing Microsoft updates at the end points against offline catalog file wsusscn2.cab that is copied to the end points from SapphireIMS central server. The CAB file gets published by Microsoft generally on second Tuesday of a month and SapphireIMS server on schedule basis downloads this file locally which later gets copied to end points during scan. .

The online method with Microsoft update catalog contains full range of patches -

  • Critical patches
  • Cumulative security and quality patches
  • Non-Security and optional updates

The offline CAB file contains only following as compared to online scan which includes more updates -

  • Security updates
  • Service packs
  • Update roll ups

Preferred method will be to use online scan provided end points are connected over the internet.If end points are not connected over internet,offline scan method can be used.