What DNS Filtering Is? How To Use It?

In the world of networking and internet security, Domain Name System (DNS) filtering is a crucial tool for managing and securing internet usage. Whether you are a business owner, a parent, or an individual looking to protect your online activities, understanding DNS filtering can help you control access to web content, block malicious sites, and enhance your overall security posture. In this blog, we will delve into what DNS filtering is, how it works, and how you can implement it effectively.

What is DNS Filtering?

DNS filtering is a process that involves using the Domain Name System to block or allow access to specific websites and online content. DNS is the system that translates human-readable domain names (like www.example.com) into IP addresses that computers use to identify each other on the network. By filtering DNS queries, you can control which domains are accessible from your network.

Domain Name System filtering works by comparing the requested domain names against a list of allowed or blocked domains. If a domain is on the blocked list, the DNS resolver will not return the correct IP address, effectively preventing the user from accessing that site. Conversely, if a domain is on the allowed list, the DNS resolver will proceed with the normal resolution process.

How Does it Work?

To understand how Domain Name System filtering works, let’s break down the process into a few key steps:

  1. DNS Query: When a user types a URL into their browser, a DNS query is sent to the DNS resolver to find the corresponding IP address.
  2. Filtering Check: The DNS resolver checks the requested domain against its filtering rules. These rules are typically based on lists of allowed or blocked domains.
  3. Response: If the domain is allowed, the DNS resolver returns the IP address to the user’s device. If the domain is blocked, the DNS resolver either returns a null response, redirects to a warning page, or returns an IP address for a different, often safe or informational, page.
  4. Access: Based on the response, the user’s device either connects to the website or is prevented from doing so.

Benefits of DNS Filtering

DNS filtering offers several advantages, including:

  • Security: It helps block access to malicious websites that could harm your network or steal sensitive information.
  • Productivity: By blocking access to distracting or inappropriate sites, it can improve productivity in workplaces and schools.
  • Parental Control: Parents can use DNS filtering to restrict access to adult content and other unsuitable sites for children.
  • Bandwidth Management: By restricting access to high-bandwidth sites, you can manage and optimize your network’s bandwidth usage.

How to Implement DNS Filtering

Implementing DNS filtering can be done at various levels, from individual devices to entire networks. Here are some common methods:

  1. Consumer DNS Filtering Services: Many DNS filtering services offer easy-to-use options for home and small business users. You can configure these by changing the DNS settings on your router or individual devices to use the DNS servers provided by these services.
  2. Enterprise Solutions: For larger organizations, enterprise-grade solutions provide robust Domain Name System filtering with advanced features like threat intelligence, detailed reporting, and integration with other security tools. These solutions often require more sophisticated setup and management.
  3. DIY DNS Filtering: Tech-savvy users can set up their own Domain Name System filtering using software like Pi-hole. Pi-hole acts as a DNS sinkhole, blocking queries for unwanted domains. This method involves setting up a small server (like a Raspberry Pi) to handle DNS queries for your network.
  4. Browser Extensions: Some browser extensions offer Domain Name System filtering capabilities, allowing users to block specific domains directly within their browser. This is a simple solution for individual users who want to control their web access without changing network settings.

Step-by-Step Guide to Setting Up DNS Filtering

Here is a general guide to setting up DNS filtering on your router:

  1. Access Router Settings: Log in to your router’s admin interface. The address, username, and password are usually provided in the router’s manual or on a sticker on the router itself.
  2. Locate DNS Settings: Find the DNS settings section, typically under network settings or internet settings.
  3. Change DNS Servers: Enter the IP addresses of the DNS servers provided by your chosen Domain Name System filtering service. For example, you might use:
    • Primary DNS: [Your chosen service’s primary DNS IP]
    • Secondary DNS: [Your chosen service’s secondary DNS IP]
  4. Save Changes: Save the new settings and restart your router if necessary.
  5. Configure Filtering Rules: Log in to the dashboard of your chosen Domain Name System filtering service and configure the filtering rules according to your needs. This may include blocking specific categories of sites, individual domains, or setting time-based restrictions.
  6. Test Your Setup: Visit a website that should be blocked based on your filtering settings to ensure it is being blocked correctly.


DNS filtering is a powerful tool for enhancing security, managing internet usage, and protecting against online threats. By understanding how Domain Name System filtering works and how to implement it, you can take control of your network and ensure a safer online experience. Whether you opt for a simple consumer solution or a more advanced enterprise setup, the benefits of Domain Name System filtering make it a valuable addition to your internet security toolkit.

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