Quick Answer
Filtering that checks where a connection is heading before it's made. DNS turns website names into addresses, so a filter sitting at that step can block a known malicious site before the browser ever reaches it.
How It Works
Every time someone clicks a link or an application connects out, a DNS lookup happens first. A DNS security service checks that destination against threat intelligence and refuses to resolve it if the domain is known to be malicious. The connection never opens.
What It Catches
Phishing pages — the fake login site behind a malicious link
Malware and ransomware download sites
Compromised devices calling home to attacker infrastructure, which often reveals an infection nobody had noticed
Categories you'd rather block for policy reasons
It Protects Laptops Anywhere
This is the part that matters most for a modern business. A firewall only protects traffic crossing your office network. DNS filtering runs on the device, so it applies at home, in a coffee shop, or on a client site.
With staff working remotely, that covers a large share of your risk that the firewall doesn't reach.
What It Won't Stop
DNS filtering blocks domains already known to be bad. Phishing campaigns frequently use domains registered hours earlier, before any threat feed has listed them. It's a strong layer that catches a lot cheaply — not a replacement for email filtering, MFA, or endpoint protection.
Example Scenario
A 140-person accounting firm faced repeated phishing attempts with convincing links. DNS security blocked access to the known malicious domains before employees reached the fake login pages, and gave the firm visibility into which connections were being attempted.
How PureStack Deploys DNS Security
We roll out DNS filtering across office and remote devices, tune the blocking policy so it doesn't disrupt legitimate work, and monitor what it catches for signs of a compromised machine.