There are a number of different ways on the MX to use content filtering to block or allow access to websites. In circumstances where different filtering options contradict one another, the following priority applies (from highest to lowest priority):
Blocked and whitelisted URL patterns.
Global content filtering rules.
Practically speaking, with these rules in mind, consider the following best practices for content filtering design:
Note: Layer 3/7 firewall rules supersede content filtering rules. Best practice is to only use content filtering for controlling web traffic, and reserve firewall rules for other applications.
For additional information on content filtering and group policies, please refer to the following articles: