June 12, 2026

DNS filtering vs proxy for endpoints: what CISOs should compare

Every endpoint web-control RFP still lists "DNS filtering" and "secure web gateway" on the same line. They are not interchangeable. The choice shapes your DORA ICT risk register, your NIS2 incident evidence, and whether users trust the control or route around it.

Where enforcement lives

DNS filtering resolves policy at the name layer. The agent binds 127.0.0.1:53, applies category rules and threat feeds locally, and sinkholes blocked domains to a branded block page on the device. No TLS termination, no PAC file, no dependency on a corporate gateway when the laptop leaves the office VPN.

A forward proxy or SWG sits in the traffic path. It can inspect URLs, decrypt TLS in some deployments, and enforce policy per session. That depth comes with certificate trust changes, latency, and a single choke point that remote workers may not reach consistently.

What auditors ask

Regulators and vendor reviewers increasingly want three things: visible enforcement (users see why something was blocked), exportable evidence (who, what domain, which policy, when), and resilience when cloud services are unavailable. DNS-layer controls with signed offline bundles answer the third item. Proxies that require always-on cloud inspection often do not.

TLS inspection triggers separate legal and works-council reviews in the EU. DNS filtering avoids that conversation while still blocking malware C2, phishing landing pages, and unsanctioned AI tools at resolution time.

When each fits

Choose DNS filtering when you need fleet-wide coverage on Windows, Linux, and macOS without decrypting traffic, when policy must work offline, and when false-positive review should start on the block page with device context. Keep a proxy or SWG when you must inspect POST bodies, scan uploads, or enforce DLP on web forms — but document that as a separate control with its own risk entry.

Many regulated firms run both: DNS at the endpoint for baseline category and threat blocking, gateway inspection only on managed networks for high-risk flows. The mistake is treating one as a substitute for the other in the ICT risk register.

Procurement trap questions

Ask vendors whether blocked users see policy reason on device, whether enforcement survives eight hours without cloud reachability, and whether block events export with domain, category, feed source, and device ID. Proxies often answer yes to the first only after TLS inspection is enabled. DNS agents built for endpoint fleets answer all three without decrypting traffic — and that distinction is what your NIS2 gap analysis should capture when web controls are scoped as critical ICT services supporting payment or trading functions.

Use our DNS policy readiness checklist to score which gaps your current stack leaves before the next DORA or ISO 27001 review.