This article explains what DUO is, and how it works.
If you are signed up for Duo through CBC, requirements are 15 characters and 3 of the 4 following: Upper Case, Lower Case, Number, Special Character. Expires every 360 days.
Without Duo, requirements are 8 characters and 3 of the 4 following: Upper Case, Lower Case, Number, Special Character. Expires every 90 days.