DNS Filtering: What It Is, Why We Use It, and How It Protects You

When you browse the internet, you usually think about websites, links, and search results. Behind the scenes, there’s another important layer working quietly to keep you safe: DNS filtering.

This post explains what DNS filtering is, why we recommend it, and how it helps protect both users and the organization.

What is DNS filtering?

DNS (Domain Name System) is what turns a website name (like example.com) into the numeric address computers use to connect.

DNS filtering checks website requests before your computer connects and determines whether the site is:

  • Known to be safe, or

  • Known (or suspected) to be malicious, risky, or inappropriate for business use

If a site is unsafe, the connection is blocked before anything loads.

Think of DNS filtering as a gatekeeper that stops you from walking into a dangerous area rather than trying to clean up afterward.

What DNS filtering helps block

DNS filtering is especially effective at preventing access to:

  • Malicious or compromised websites

  • Phishing and fake login pages

  • Known malware and ransomware sites

  • Command-and-control servers used by attackers

  • Scam, fraud, and impersonation sites

Because this happens at the DNS level, it works even if:

  • A link is clicked accidentally

  • A website looks legitimate

  • Malware tries to “phone home” in the background

Why DNS filtering matters

Many cyber incidents begin with a simple action:

  • Clicking a bad link

  • Visiting a compromised website

  • Typing a slightly incorrect web address

DNS filtering reduces risk by:

  • Blocking known bad destinations automatically

  • Stopping threats early in the attack chain

  • Protecting users even when mistakes happen

It’s one of the most effective preventive security controls available.

What happens when a site is blocked

If you attempt to visit a blocked site, you may see:

  • A block page explaining the site was restricted

  • A message that access is denied

  • A prompt to contact IT if you believe it’s an error

This does not mean:

  • You did something wrong

  • You’re being monitored personally

  • Your device is infected

It simply means the site failed a safety check.

How DNS filtering works with other security tools

DNS filtering is not a replacement for antivirus or other protections — it’s part of a layered security approach.

Together with:

  • Endpoint protection

  • Email filtering

  • Firewalls

  • Patch management

DNS filtering adds another layer that helps stop threats before they reach your device.

Why organizations enforce DNS filtering

DNS filtering supports:

  • Safer browsing for users

  • Reduced risk of malware infections

  • Protection against phishing attacks

  • Better visibility into widespread threats

It also aligns with widely accepted security best practices and expectations found in frameworks such as HIPAA, CMMC/NIST, PCI-DSS, and general cybersecurity guidance.

Common questions

Can legitimate sites be blocked by mistake?
Occasionally, yes. If a site is incorrectly blocked and is needed for business, we can review and allow it.

Does DNS filtering slow down the internet?
No. DNS filtering operates quickly and typically has no noticeable impact on browsing speed.

Does this track what I do online?
DNS filtering focuses on protecting the organization and blocking known threats, not monitoring individual browsing habits.

Our recommendation

We recommend DNS filtering as a foundational security control for all managed devices.

It quietly protects users in the background, helps prevent phishing and malware, and reduces the chance of security incidents caused by malicious websites.

If you ever encounter a blocked site you believe is required for work, or have questions about how DNS filtering works, please let us know and we’re happy to help.

Al Davis