Go to Content Filtering > Domains to view and manage all of your allowed and blocked domains.
Allowed Domains: If you block access to a particular category, e.g. Spyware and Malicious Sites, all websites within that category will be blocked. However, you can allow access to a website that is included in a blocked category by adding it as an Allowed Domain.
Blocked Domains: If you allow access to a category, e.g. Art, all websites within that category will be allowed. However, you can block access to a website that is included in an allowed category by adding it as a Blocked Domain.