When Active Directory deletes an object from the directory, it does not physically remove the object from the database. Instead, Active Directory marks the object as deleted by setting the object’s isDeleted attribute to TRUE, stripping most of the attributes from the object, renaming the object, and then moving the object to a special container in the object’s naming context (NC) named CN=Deleted Objects. The object, now called a tombstone, is invisible to normal directory operations.
Obviously, objects don’t remain in the CN=Deleted Objects container forever. The default tombstone lifetime is 60 days for forests initially built using Windows® 2000 and Windows Server 2003, and 180 days for forests that were initially built with Windows Server 2003 SP1. Every 12 hours, each domain controller starts a garbage collection process. (This can be changed by setting a new value for the garbageCollPeriod attribute of the CN=Directory Service,CN=Windows NT, CN=Services,CN=Configuration,DC= object.) This garbage collection scans all of the tombstones on the DC and physically deletes any that are older than the tombstone lifetime.
The Deleted Objects container is hidden and cannot be viewed by using Active Directory Users and Computers and ADSIEDIT.MSC. But you can use LDP.EXE.
Note:There is another tool names ADRestore.exe which will do the same as LDP.exe