CMMC Practice SC.4.229: Utilize a URL categorization service and implement techniques to enforce URL filtering of websites that are not approved by the organization.
CMMC CLARIFICATION (Ref CMMC – Appendix B)
Organizations shall have the ability to prevent access to URLs the organization has determined should not be accessed for policy or security reasons. URL filters typically are a blacklist of URLs that block access to known bad sites. Categorization services identify websites according to a set of content attributes and allow organizations to allow or disallow access to entire classes of websites. In addition, organizations may choose to block access to uncategorized sites, which may represent malicious sites. The filters and categories should be updated dynamically through an intel subscription as well as manually.