1. On the Windows 2008 Domain control, log on as a domain Administrator account, run “gpmc.msc” to open Group Policy MMC.
2. Click Default Domain Policy.
3. On the pull down menu choose Action, click Edit.
4. Locate Computer Configuration\Windows Settings\Security Settings\Account Policies\Password Policy, set the “Minimum password length” and “Password must meet complexity requirements” policy.
Watch the video below.