DNS Content Filtering Explained

DNS content filtering is a method used to carefully control the types of web content that can be accessed via wired or wireless networks. DNS content filtering is used by internet service providers to ensure customers cannot access any content that violates laws in their country. Businesses use DNS content filtering to enforce their internet usage policies and prevent employees from accessing malicious websites.

How Does DNS Content Filtering Work?

When you want to visit a website, you type the URL into your web browser and the website is loaded. The process takes just a fraction of a second, but several steps must first be completed behind the scenes. A computer cannot find a website on its own, it requires a check to be performed against the Domain Name System (DNS). The DNS is used to match the domain name with its IP address. Without the IP address, the website cannot be located.

First a query is sent to a recursive DNS server, which makes contact with other servers to find the IP address of the website. If the website exists, the IP address is found and is provided to the browser which then loads the website.

DNS content filtering occurs at the DNS lookup stage. In a fraction of a second, a series of checks are performed to determine if the user should be allowed to visit a particular website or webpage. Checks will be performed against several blacklists (RBLs) of webpages which, for various reasons, are prohibited. Blacklists are maintained by several organizations. For example, the Internet Watch Foundation maintains a blacklist of webpages that contain content related to child abuse and their blacklist is used to minimize the availability of online sexual abuse content. Blacklists are also maintained for websites and webpages that are used to distribute malware and conduct phishing attacks and other forms of fraud.

In addition to blacklists, checks of websites are performed on the fly. These checks are important as new web content is constantly being uploaded and the content of webpages can change. If websites are found to violate pre-defined policies, access to those resources will be blocked.

DNS content filtering sees filtering controls applied before any web content is downloaded. If the website passes all the checks, the content will be displayed in the user’s browser. If the checks fail, instead of the IP address being provided to the browser, it will be directed to display a local DNS block page. The block page explains that the webpage cannot be displayed, along with the reason why.

DNS content filtering solutions allow policies to be applied for the entire organization, for different offices, and for user groups, roles, and individual users. The marketing department will naturally need to be able to access social media websites, but other users may be prevented from accessing those sites in an effort to curb cyberslacking. Modern web filtering solutions have highly granular controls, so it is possible to exercise precise control over the types of content that can be accessed.

DNS Based Content Filtering for SMBs and MSPs

TitanHQ is the leading provider of cloud-based email and web security solutions for SMBs and managed service providers (MSPs) serving the SMB market. SpamTitan is a powerful email security solution that blocks spam email and prevents phishing emails and other malicious messages from reaching inboxes.

WebTitan is a DNS filtering solution that protects against the web-based component of phishing scams and prevents end users from visiting inappropriate websites and malicious webpages. WebTitan has coverage of more than 6 billion webpages on more than 500 million websites. The solution allows precision control over web content and provides insights into the activities of users in real time and through an extensive suite of pre-configured and customizable reports.

SpamTitan and WebTitan are easy to implement, use, and maintain, and together they provide excellent protection from phishing, spear phishing, malware, ransomware, viruses, and botnets.

For further information on these products, for details of pricing, and to book a product demonstration or register for a free trial of either solution, give the TitanHQ team a call today.