I had to do some fixed to my password tool to cope with forums that used a very short field some choked on even a short 128-bit password so now running servers ad-nauseum under Hyper-V, how strong can I protect the administrator account?Windows MVP, XP, Vista, 7 and 8. More people have climbed Everest than having 3 MVP's on the wall. Hardcore Games, Legendary is the only Way to Play Developer | Windows IT | Chess | Economics | Vegan Advocate | PC Reviews

Upper range is 128 bit ( 127 practical scenario) http://msdn.microsoft.com/en-us/library/ms680851(VS.85).aspx and if you are testing on Local accounts it is 28 character long.

I use remote desktop to manage my virtual machines and as such they are equivalent I am aware that Windows 8 can use at least 16 symbols which is its limit Windows MVP, XP, Vista, 7 and 8. More people have climbed Everest than having 3 MVP's on the wall. Hardcore Games, Legendary is the only Way to Play Developer | Windows IT | Chess | Economics | Vegan Advocate | PC Reviews

Per the link Sainath provided, the limit is 128 bytes (characters) for passwords in AD. When I tested in the past I was able to assign a 127 character password, but the GUI did not allow 128. 127 bytes is 1016 bits. Richard Mueller - MVP Directory Services