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Forefront Endpoint Protection – Synchronization of Definition Update Releases with WSUS/ConfigMgr

The following information can be used to reduce delays between the release of new FEP definition releases, and when the new definitions are available to WSUS/Configuration Manager.

Delta FEP Definitions

  • Released daily (every 8 hours) via Windows Update and WSUS at:
    • 3 AM (EST)
    • 11 AM (EST)
    • 7 PM (EST)


Rebased FEP Definitions

  • Released once a month. (“Patch Tuesday”)
  • Includes antivirus and antispyware definitions
  • Accumulation of previous months base file and delta definitions that were released since the previous rebase.


The frequency at which the updates are available to target computers is dependent upon a couple of factors:

  • The frequency at which WSUS synchronizes with Windows Update.
  • The process used for approving the updated definitions for deployment.



Reference: KB977939 – Description of Forefront Endpoint Security Definition Updates

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Senior Premier Field Engineer - Microsoft Corporation Mark has been working as a Manageability PFE (SCCM/SCOM) for Microsoft, since April 2006, supporting various CONUS/OCONUS engagements for the federal government. Prior to this, he has worked with SMS/SCCM for various other organizations since approx. 1997 (starting with SMS v1.2). A native Texan, Mark lives in Virginia with his wife Christy. They have three children and one grandchild. LinkedIn Profile:

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