What is DNS filtering and does my business need it?

Every time you type a website address or click a link, your computer makes a DNS request. DNS - the Domain Name System - is the internet’s phone book, translating human-readable names (like google.com) into the IP addresses computers actually use.

Here’s why that matters for your security: 79% of cyberattacks use DNS at some point in the attack chain. DNS filtering intercepts those requests and blocks the dangerous ones before the malicious website ever loads.

It’s one of the simplest, cheapest, and most effective security tools available - and most small businesses don’t have it.

How DNS Filtering Works

Without DNS filtering:

1. Employee clicks a phishing link in an email
2. Their computer asks a DNS server: “What’s the IP address for totally-legitimate-bank.com?”
3. The DNS server responds with the IP address
4. The browser loads the malicious website
5. The employee enters their credentials, which are stolen

With DNS filtering:

1. Employee clicks the same phishing link
2. Their computer asks the DNS filter: “What’s the IP address for totally-legitimate-bank.com?”
3. The DNS filter checks its threat intelligence database and recognizes this domain as malicious
4. Instead of the malicious site, the employee sees a block page explaining the site was blocked for security
5. Crisis averted

All of this happens in milliseconds, before any malicious content reaches the employee’s device.

The Threat Landscape: Why DNS Filtering Matters Now

The numbers from recent DNS security reports paint a clear picture:

• Threats grew 30% between 2024 and 2025 on major DNS filtering networks
• The average internet user encounters 66 threats per day, up from 29 the previous year
• 1 in every 174 DNS requests is malicious, up from 1 in 1,000 in previous reports
• Over 200 million malicious DNS queries are blocked daily on a single major filtering network
• 25% of newly observed domains are classified as malicious or suspicious
• Organizations suffer an average of 7 DNS attacks per year, at a cost of $942,000 per attack

Phishing queries alone have increased by 203%. The scale of DNS-based threats is accelerating faster than most businesses realize.

What DNS Filtering Blocks

Malicious Content

• Phishing sites that steal credentials
• Malware distribution sites that download viruses and ransomware
• Command and control (C2) servers that attackers use to communicate with compromised devices
• Newly registered domains that are statistically more likely to be malicious (over 25% of new domains are suspicious)
• Typosquatting domains designed to catch misspellings of popular sites

Inappropriate Content

Beyond security, DNS filtering can block:

• Adult content
• Gambling sites
• Social media (during work hours, if desired)
• Streaming media
• Other categories based on your acceptable use policy

Shadow IT and Data Exfiltration

DNS filtering provides visibility into:

• Unauthorized cloud services employees are using
• Potential data exfiltration through DNS tunneling
• Bandwidth-heavy services affecting network performance

Why DNS Filtering vs. Other Security Tools?

DNS filtering isn’t a replacement for other security tools - it’s a complementary layer that catches threats others miss.

Security Layer	What It Does	Limitation
Email security	Filters malicious emails	Doesn’t protect against threats from web browsing, ads, or social media links
Endpoint protection (EDR)	Detects malware on devices	Only acts after malicious content reaches the device
Firewall	Controls network traffic	Doesn’t inspect DNS traffic by default
DNS filtering	Blocks threats before they load	Doesn’t inspect file contents or email attachments

DNS filtering works at the network level, protecting every device that uses your network - including IoT devices, guest devices, and personal phones on your WiFi that don’t have endpoint protection installed.

The “First Line of Defense” Advantage

Think of security as a series of gates:

1. DNS filtering blocks the connection before any content loads (Gate 1)
2. Firewall inspects network traffic patterns (Gate 2)
3. Email security scans messages and attachments (Gate 3)
4. Endpoint protection catches malware that reaches a device (Gate 4)

The earlier you stop a threat, the less damage it can do. DNS filtering is Gate 1 - the earliest possible interception point.

Implementation: Easier Than You Think

DNS filtering is one of the simplest security tools to deploy:

Option 1: Network-Level (Recommended for Offices)

Change the DNS settings on your router or firewall to point to the filtering provider’s DNS servers. Every device on your network is instantly protected - no software installation required.

Setup time: 15-30 minutes

Option 2: Endpoint Agent (For Remote Workers)

Install a lightweight agent on laptops and mobile devices. The agent routes DNS queries through the filter regardless of which network the device is on - office, home, coffee shop, or hotel.

Setup time: 5-10 minutes per device (or deploy via management tools)

Option 3: Hybrid

Use network-level filtering in the office and endpoint agents for remote workers. This is the most comprehensive approach for businesses with hybrid workforces.

What Good DNS Filtering Looks Like

When evaluating DNS filtering solutions, look for:

• Real-time threat intelligence updated continuously (not daily or weekly)
• Category-based blocking for acceptable use policy enforcement
• Customizable allow/block lists for business-specific needs
• Reporting and analytics showing blocked threats and browsing patterns
• Roaming client support for remote and mobile workers
• Low latency - filtering shouldn’t noticeably slow down browsing

Popular Business DNS Filtering Solutions

Most managed IT providers deploy DNS filtering as a standard part of their security stack. Common solutions include Cisco Umbrella, DNSFilter, and Cloudflare Gateway - all designed for business use with centralized management.

Cost and ROI

DNS filtering is remarkably affordable:

Company Size	Typical Monthly Cost	What You Get
10-25 users	$30-75/month	Network + roaming protection
25-50 users	$75-150/month	Full protection with reporting
50-100 users	$150-300/month	Advanced features, custom policies

Compare that to the $942,000 average cost of a DNS attack and the ROI is obvious. DNS filtering is consistently one of the highest-return security investments a business can make.

Common Questions

”Won’t it block legitimate websites?”

Good DNS filtering solutions have extremely low false positive rates. And you can always whitelist specific domains if something gets blocked incorrectly. Most solutions let you do this in seconds from the block page itself.

”Can employees bypass it?”

With network-level filtering, it’s difficult to bypass without technical knowledge. With endpoint agents, it requires administrator access. For most businesses, this level of enforcement is sufficient. For high-security environments, pair DNS filtering with other controls.

”Does it slow down the internet?”

No. Modern DNS filtering adds 1-5 milliseconds of latency - imperceptible to users. Many users actually experience faster browsing because filtering providers operate high-performance DNS infrastructure.

The Bottom Line

DNS filtering blocks threats before they reach your network, protects every device (including those without endpoint protection), takes minutes to deploy, and costs less than your monthly coffee budget.

When 35% of companies still don’t use DNS traffic filtering, and threats are growing 30% year over year, it’s one of the easiest security gaps to close. If you only do one new security thing this quarter, make it DNS filtering.

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Want to add DNS filtering to your security stack? Contact us to get started with network-level protection.