Though DyKnow URL Filtering supports filtering web traffic over SSL, it does not currently support filtering sites that utilize a "wildcard" SSL certificate in version 5.6. This has been resolved in DyKnow 5.7.
Wildcard certificates are SSL certificates that are valid for all subdomains on the domain specified. Most SSL certificates are only for a specific server on a domain.
Given a wildcard certificate of *.school.com, you can create a URL filtering allows a rule of *.school.com, which would allow all subdomains of school.com. If a wildcard SSL certificate is applied to subdomain.school.com, however, the page will not load and be blocked.