DNS filtering is the process of using the domain name System to block malicious websites and filter out harmful or inappropriate content, keeping a company's data secure while also allowing it to control what its employees can access on a company-managed network. To understand how DNS filtering works, you need to understand what the domain name system is.

The domain name system matches domain names with IP addresses. A service that converts easy-to-remember domain names into machine-recognizable IP addresses. Users can access websites without having to remember complex IP addresses. When a user enters a domain name, the device sends a query to a DNS resolver, which looks for and returns the corresponding IP address, which the device then uses to connect to the server and load the website content. DNS is the key to network access, and it is also the basis for implementing DNS filtering and controlling access content.

DNS filtering sends all DNS queries to the DNS resolver. The DNS resolver can also act as a filter to prevent users from resolving some domain queries tracked in the blacklist. DNS filtering services can also use permissive lists instead of blacklists. DNS filtering can blacklist Web resources by domain name or IP address: By domain name: The DNS resolver does not resolve or look up the IP address of some domain names at all; By IP address: The DNS resolver tries to resolve all domains, but if the IP address is on the blacklist, the resolver will not send it back to the requesting device.

DNS filtering blocks malware and phishing attacks by blocking malicious and phishing websites:

Blocking malicious websites: DNS filtering blocks users from accessing web pages that might automatically download malware, preventing code such as JavaScript from penetrating users' devices.

Blocking phishing sites: By identifying and blocking counterfeit sites, DNS filtering protects users from revealing login credentials.

Dependency identification: DNS filtering relies on identifying malicious IP addresses or domain names, but faces the challenge of attackers quickly generating new domain names.

Blocking Banned content: by blacklisting the IP address or domain name of objectionable content, or allowing access only to websites on the white list.

Secure DNS Server: As part of DNS filtering, secure DNS servers such as Cloudflare's 1.1.1.1 provide privacy protection and clear query logs.

Enhanced DNS security: DNSSEC guarantees the accuracy of DNS information, while DNS over TLS and DNS over HTTPS encrypt DNS queries and prevent attackers from tracking user behavior.

DNS filtering and Web filtering: DNS filtering is a kind of Web filtering. Other Web filtering methods include URL filtering, keyword filtering, and content filtering.

DNS filtering blocks malicious or banned websites and apps at the DNS level so that they cannot be loaded onto user devices, keeping websites and apps secure.