A. Normally the answer is 180 days, but it can actually vary depending on which version of Windows and what service pack you used to create the AD.
The default tombstone lifetime (TSL) values are:
Windows 2000 or Windows Server 2003 RTM: 60 day TSL
Server 2003 SP1: 180 day TSL
Server 2003 R2: 60 day TSL (This confuses most people. Essentially, the 180 day change was backed out in Server 2003 R2.)
Server 2003 SP2, Server 2003 R2 SP2, and later:180 day TSL
Related Reading:
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