What is DNS Based Content Filtering?

When an Internet user types the address of a website into their browser bar, or clicks on a link to the website, a process starts to obtain the IP address of the target website so the browser can communicate with the website and the Internet user can access its content. This process is known as the Domain Name System, or DNS.

DNS based content filtering is simply another way of saying that an Internet filter allows or blocks access to the target website´s content according to the website´s IP address rather than its domain name. By allowing or blocking access by IP address, rather than domain name, the filtering process is much more efficient and results in imperceptible latency.

Free 15 Day trail licence


How Does the Filter Know Which Websites to Block?

There are a number of ways in which filters block access to websites. Some of these are default operations in Internet filters, whereas others are administrator-controlled. The more methods used, the safer the browsing experience – and, depending on the way the DNS based content filtering service is set up, more methods does not necessarily mean more administration.

  • Our cloud based Filters check IP addresses against a database of websites known to harbor malware or ransomware, or that are vulnerable to exploitation.
  • Spam and Phishing Filters check IP addresses against a database of website URLs that have been found in spam emails and are candidates for phishing websites.
  • Category Filters enable administrators to block access to website content depending on the nature of their content (i.e. pornography, racial hatred, etc.).
  • Keyword Filters can be used to block access to websites or website applications by specific words in the content of the website (i.e. “chat”, “Netflix”, “milf”, etc.).
  • Administrator-controlled Blacklists and Whitelists block or allow access to specific websites as determined by the administrator.

Types of DNS filter

  • Router based flat filter, with option of a antiDNS avoidance option
  • Active Directory filtering, which is based on the users active directory logon profile.

The Flat filter option gives all users on the network the same level of filtering, this type of filter requires no extra hardware, just a simple change of the dns settings in the router or server. AntiDNS avoidance, if you routers firewall supports port 53 redirect options then you can avoid end users changing the DNS settings in their devices, this will for the end user devices to always use your Flashstart DNS filter.

The Active Directory based filter, If you run active directory for your business, school, office, health authority or council offices, then the active directory filter will give you that extra level of granular filtering, With our Flashstart AD filter you can set individual levels of filtering per user or a group, for explain, in a school the head teacher would like very loose level of filtering, but the teaching staff need access to some site but not all, and the students can have a even tighter level of filtering only give them access to educational site etc.

How a DNS Based Internet Filter can Benefit Businesses

The obvious benefit to businesses is that a DNS based Internet filter is an effective way to prevent malware, ransomware and phishing attacks. In addition, there are numerous examples of how a DNS based Internet filter can be commercially advantageous in terms of increasing productivity, reducing HR issues in the workplace, and providing users with a safer browsing experience. Here´s a few:

  • A study looking into “cyberloafing” found that 32% of employees spend more than two hours a day visiting non-work related websites.
  • In many business, persistent Internet abuse is a dismissible offence. A DNS based Internet filter helps businesses avoid this HR issue.
  • Retail businesses proving a public Wi-Fi service, can take advantage of a DNS based Internet filter in order to provide a family-friendly environment.

Download our brochure

Download Tech spec


I need broadband are Flashstart’s  master licence distribution partner in the uk, please contact us for prices and re seller options.

Price for filtering is based on a per user basis per year.


  • This field is for validation purposes and should be left unchanged.