DNS blocking is a simple filter for where devices are allowed to go on the internet. When a user tries to visit a domain on the block list, the DNS resolver refuses or sends them nowhere - so risky or unwanted sites never load.
Your device asks a DNS resolver for a site’s IP.
The resolver checks policies/lists first.
If the domain is blocked (malware, phishing, adult, gambling, etc.), the lookup is denied or redirected to a safe page.
Security: stop malware/phishing domains before connections happen.
Productivity & policy: block gambling, pirated content, or shadow IT at work/school.
Parenting: filter adult sites and risky downloads at home.
Not a silver bullet: won’t see encrypted IP-only traffic or block VPNs.
Overblocking happens: legit sites can be mislabeled—allowlist when needed.
Bypass risk: users can change DNS or use DoH/DoT unless you enforce it on the network.
Choose a reputable DNS filter (supports categories, malware feeds, custom lists).
Enforce at the router/firewall: force all DNS to your resolver; block outbound 53/853 to others.
Turn on DoT/DoH to your chosen resolver to prevent tampering.
Start in monitor mode for a week, review hits, then tighten.
Maintain allow/deny lists and review alerts for false positives.