Serena Raymond
February 18, 2020 in
DNS

DNS Filtering: How Does It Work?

Whether you’re just learning about DNS for the first time or have had DNS threat protection for years, how much do you really know about DNS filtering? This blog post will cover DNS basics, what DNS filtering is, and why everyone needs it.

dns filtering

First things first: What is DNS?

You might not know it, but you use DNS every single day. DNS stands for Domain Name System. It’s often referred to as the phonebook of the internet.

When you want to visit a website, you type in the domain name of the site and get there pretty much instantaneously. But what you’re really doing is asking a DNS server “What is the IP address of Facebook.com?” The DNS server responds with the IP address and takes you to Facebook.

DNS translates the domain name into an IP address for us, so we don’t have to memorize a long number.

How did we land on this system?

In the ‘70s, the internet’s precursor was called ARPAnet. ARPA stood for Advanced Research Projects Agency Network.

A critical component of ARPAnet was a file called “HOSTS.TXT.” This was a single file housed at the Stanford Research Institute called “HOSTS.TXT” which, true to its name, held all of the information about the hosts. Similar to the modern-day internet, users of ARPAnet could access the “host files” (what we would call “domains”), but everything was routed through a single file, and a single computer.

As you can imagine, updating this HOSTS.TXT file became cumbersome. The system couldn’t scale, and it was relatively easy to make the system go down. For instance, there was nothing in place preventing someone from adding a duplicate “host” to the master file. Imagine if someone tried to add a second “Facebook.com” to the internet! Likely, Facebook would be down for a little while until someone fixed the mistake.

Because there was nothing in place to prevent this duplication, affected hosts and systems could be taken offline if someone made the mistake of adding, for instance, a second “Facebook.com”.

From this experiment, DNS was born. DNS is a hierarchical and decentralized naming system that ensures all names are completely unique. And because DNS servers are distributed (i.e., not located in a single place), it has allowed the internet to grow the way it has.

We’re now at nearly 2 billion domains!

What is DNS filtering (and how does it work)?

If DNS is the phonebook, think of DNS filtering as a caller ID system that can enable call blocking.

With DNS filtering, when you type in a website’s domain, a filtering process takes place between the IP address being retrieved and the page being displayed. This filtering process categorizes the site into a variety of groupings that include news and media, social networking, malicious, illegal content, and much more.

Businesses put DNS filters in place to block employees or guest Wi-Fi users from specific sites. A business might choose to block social media sites during work hours for their employees or illegal content for both employees and public Wi-Fi guests. A DNS filtering system will always block users from malicious content.

Once a website has been categorized, the filter will either display the page or block it depending on the parameters set up ahead of time by the business. So if you’re trying to access Facebook during work hours at a company that has blocked the site, you’ll see something like this:

lightning fast DNS

Like this example, block pages are usually customizable. If you encounter a company block page, you might see your company’s logo with a note that they’re the ones who are blocking you.

Why do we need to filter DNS?

Though we touched on it in the previous section, DNS filtering is not just about employers blocking sites they don’t want their employees to access. It’s also a very important cybersecurity measure that prevents you from accessing malicious sites that can administer phishing, ransomware, or cryptojacking attacks.

Unfortunately, there are a lot of people who compromise websites in order to trick people into handing over their login credentials, scamming them out of money, and causing businesses to be shut down.

And if you remember, there are almost 2 billion domains out there. And roughly 200,000 new domains every day. Those are a lot of opportunities to run into a malicious site without realizing it.

Even previously “safe” websites aren’t always safe, as they may become compromised. That’s why going with a DNS protection solution with an advanced AI is a must. It keeps employees and guest Wi-Fi users safer because it doesn’t just check a list of safe domains, it actually scans the page.

Omitting DNS filtering from your cybersecurity is a huge business risk. It puts pressure on employees to assess risks on their own, when they might not have the skills or training to do so.

Get your free trial of DNSFilter today to prevent you and your employees from accessing malicious content.


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