When you enable the Password must meet complexity requirements GPO (Group Policy Object) at in the Default Domain Policy at Computer Configuration / Windows Settings / Security Settings / Account Policies / Password Policy, passwords must meet the following minimum requirements:
- May NOT contain all, or any portion of the user's account name.
- Must be at least 6 characters.
- Must contain characters from three (3) or the following categories:.
- Uppercase characters (A through Z).
- Lowercase characters (a through z).
- Numbers (0 through 9).
- Special characters (!, $, #, %).