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Starting in Windows 7/2008R2, there are potential compatibility issues with using domain user accounts ending with the dollar sign ($) as a service account. Managed service accounts are identified by ending in a dollar sign ($). The system may evaluate the account as a managed service account and block the change.
The sAMAccountName attribute of a computer object is the NetBIOS name of the computer with a trailing dollar sign, "$", appended. Besides flagging the object as a computer (which has class user), it also helps ensure uniqueness. The sAMAccountName value must be unique in the domain. Note, the Common Name of computer objects (the value of the cn attribute) does not have a trailing "$", but cn also does not uniquely identify the object in AD. The Common Name only needs to be unique in the OU or container.
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