Some basic filters block domain names (e.g., "www.facebook.com") but not the underlying IP address. If an employee obtains the IP address (e.g., via a ping from an external network), they can enter it directly. This method is rarely effective against modern deep packet inspection (DPI) firewalls, which analyze content regardless of addressing.
Even if you successfully reach a site, IT administrators often have logs showing that you accessed a workaround tool, which can be a red flag. view blocked websites at work