DNS blocking refers to a technique that restricts access to certain websites and online content. One of its primary uses is to help organizations prevent employees from accessing nonwork-related websites.

The technique is also used in school and at home to control what websites children can visit. Also called “DNS filtering” and “Internet content filtering,” DNS blocking helps improve productivity, enhance cybersecurity, and protect user privacy.  

Read More about DNS Blocking

DNS blocking was first implemented in 1997 to block spam emails from known malicious IP addresses. The succeeding sections talk more about DNS blocking.  

Why Is the Process Called “DNS Blocking”?

DNS blocking git its name because website or content filtering happens at the DNS level. DNS stands for “Domain Name System,” which works as the Internet’s phone book. It translates the website names you type into your browser into IP addresses that computers better understand.

To keep people from visiting certain websites, you need to ensure that the DNS won’t return the IP addresses associated with them.

Imagine a scenario in a restaurant where the kitchen ran out of some ingredients. The chef, therefore, wouldn’t want customers to order certain dishes. He could tell the waiter to “block” such orders by informing customers about the problem and offering alternatives.

How Does DNS Blocking Work?

Here’s how DNS filtering works.

How DNS Blocking Works
  1. When you type a URL into your browser, your computer sends a request to a DNS server to get the IP address for that link.
  2. If the DNS server was configured to block certain domain names, it will either fail to return an IP address or return one for a different page–often a block page notifying users that the site they’re trying to reach is not accessible.
  3. As a result, your browser can’t find the server where the website is hosted and won’t load the website.

Why Is DNS Blocking Implemented?

DNS filtering can serve several purposes, including the following:

  • Parental control: Parents can use DNS filtering to prevent children from accessing inappropriate websites, offering a level of parental control over their Internet usage.
  • Corporate policy implementation: Companies can use DNS blocking to prevent employees from accessing nonwork-related websites that could decrease productivity.
  • Legal compliance: In some countries, Internet service providers (ISPs) use DNS blocking to restrict access to websites deemed illegal by the local government.
  • Intellectual property protection: DNS filtering helps prevent users from accessing sites that host illegal content or violate copyright laws.
  • Security measure implementation: DNS filtering can restrict access to malicious websites that host malware, serve as phishing pages, or play a part in other cyber threats.

Aside from parents, schools, and ISPs, several other entities use DNS filtering. They include government entities, cybersecurity firms, and businesses across various industries.

What Benefits Does DNS Blocking Provide?

DNS blocking offers several benefits, including:

  • Enhanced cybersecurity: DNS filtering can protect networks from threats by preventing users from accessing known malicious websites. It blocks domains associated with phishing, malware, botnet, and other cyber attacks.
  • Improved productivity: For businesses and educational institutions, DNS filtering can prevent users from accessing nonwork-related or distracting websites, thus enhancing productivity.
  • Efficient bandwidth allocation: In some cases, DNS blocking can help network administrators manage bandwidth by blocking access to high-bandwidth-using websites or services like streaming platforms, especially in environments with limited bandwidth.
  • Privacy protection: DNS filtering can prevent access to websites that track user data, thus enhancing privacy protection.

What Disadvantages Does DNS Blocking Pose?

Despite the benefits it provides, DNS filtering also comes with potential drawbacks, such as:

  • Overblocking: It can unintentionally block access to legitimate resources. In offices, overblocking can affect the employees’ quality of work since they may not have access to pertinent information because of DNS filtering.
  • Underblocking: Some undesirable content can remain accessible. This situation can be detrimental, specifically when websites with adult content are not completely blocked at home or in school.

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It’s essential to understand that DNS blocking is not foolproof. Individuals who use alternative DNS servers or virtual private network (VPN) services can bypass it.

Key Takeaways

  • DNS blocking, also known as “DNS filtering,” restricts access to specific websites and online content.
  • It serves various purposes, including parental control, corporate policy implementation, regulatory compliance, intellectual property protection, and cyber threat prevention.
  • The technique enhances network security, improves productivity, allows efficient bandwidth allocation, and aids in privacy protection.
  • It can lead to overblocking, unintentionally making valuable resources inaccessible.
  • It can lead to underblocking, leaving some undesirable content accessible.