After 10 unsuccessful logon attempts (wrong password), the user will need to solve a CAPTCHA dialog as part of logon.
After a further 10 unsuccessful logon attempts (wrong password) and correct solving of the CAPTCHA dialog, the user will be locked out for a time period. Further incorrect passwords will result in an exponential increase in the lockout time period.

Note: This does not affect your ability to log in using your CougarNet account for other services.

See Microsoft TechNet website for more details: http://technet.microsoft.com/en-us/library/jj943764.aspx