How It Works

ThreatSTOP's DNS firewall product is fully customizable using our standard portal and UI. It only takes a few minutes for subscribers to select one of our standard policies or create their own custom policy in our portal. Policies can specify different rules so that, for example, attempts to contact botnet C&C servers can simply be denied while users who click on phishing links see a redirection to a walled garden.

These new rules, customized for their precise policy name, are obtained from the portal and are added to the BIND DNS server configuration files. The DNS server automatically downloads the policy and applies it to all lookups it receives. The policy is automatically updated (by default this is every two hours) so that the policy can block new threats and no longer block access to locations that have been remediated.


RPZ takes action based on the domain name queried (QNAME), the IP address returned (RPZ IP) or the fully qualified domain name (FQDN) or IP address of any of the name servers used in the resolution process (NS IP and NS DNAME). Depending on the match the name server can opt to:

  • Report an error (NXDOMAIN or NODATA).
  • Not return anything (DROP).
  • Return a static IP address (for example,
  • Return a walled garden name (CNAME walledgarden.local).
  • Return the true data (PASSTHRU) - typically used to override a specific host/subdomain in an otherwise suspicious domain.