ThreatSTOP Blog

Protective DNS in Practice: Turning Guidance into Action with ThreatSTOP

Written by Joel Esler | October 7, 2025

In recent months, federal agencies including NSA and CISA have underscored a critical point: Protective DNS (PDNS) is no longer optional—it’s essential. Attackers continue to exploit DNS as their first step, whether for phishing, malware callbacks, or domain-generation algorithms (DGAs). The guidance is clear: organizations must establish controls that ensure DNS traffic can’t be abused.

At ThreatSTOP, we translate that guidance into immediate, practical protection for enterprises, without hardware, without lengthy deployments, and without adding operational complexity.

1. Force All DNS to Authorized Resolvers—and Block the Rest

CISA and NSA recommend a foundational control: ensure every device in your environment points to authorized resolvers, and block unauthorized DNS traffic, including encrypted DNS channels that can be used to evade monitoring.

How ThreatSTOP helps:

  • DNS Defense Cloud and DNS Defense become your policy-enforcing resolvers. Every query from your network routes through our service, where malicious or policy-violating lookups are stopped, in the cloud, or on prem.  Block output DNS queries to everything except the ThreatSTOP enabled resolver.  Our default policy disabled third-party DOH services.

This creates a “clean pipe” for DNS: authorized, controlled, and policy-enforced.

2. Apply Intelligence, Not Just Resolution

Protective DNS isn’t just about pointing to a resolver, it’s about stopping malicious lookups before they connect. Federal guidance stresses the need for curated threat intelligence and suspicious domain heuristics.

How ThreatSTOP helps:

  • Our Security, Intelligence, and Research Team curates thousands of feeds, both 3rd party and proprietary, ensuring coverage of malware, phishing, and command-and-control infrastructure.

  • Customers can layer in their own allow/deny lists, giving fine-grained control to meet compliance and operational needs.

  • Dynamic categories like “newly seen domains” or “DGA-suspect” domains are enforced automatically, closing gaps before adversaries exploit them.

3. Watch NXDOMAINs—A DGA Early Warning

One often overlooked signal is the humble NXDOMAIN. Bots using DGAs flood the resolver with failed lookups, generating spikes long before a working C2 domain is hit.

How ThreatSTOP helps:

  • Our systems monitor NXDOMAIN spikes across customer environments and surface anomalies.

  • This lets security teams detect stealthy infections at the reconnaissance stage, before data is exfiltrated or ransomware is deployed.

4. Deploy in Hours, Not Months

Unlike legacy security appliances, PDNS should be frictionless to adopt. NSA/CISA guidance notes the “simple setup” path: repoint your resolvers to a Protective DNS service and enforce egress controls. ThreatSTOP has designed exactly for that model.

How ThreatSTOP helps:

  • No hardware required. Point resolvers (on-prem or cloud) to ThreatSTOP, or configure DHCP/DNS settings so all clients resolve through our service.

  • Built-in integrations for Active Directory, VMware, and cloud VPCs speed adoption.

  • Updates happen in real time—no patch cycles or reboots.

5. Auditability and Compliance Evidence

Protective DNS also simplifies audits and investigations. Auditors want proof of controls; security teams want searchable history of DNS activity and policy enforcement.

How ThreatSTOP helps:

  • DNS query logs (anonymized and retained 30 days in DNS Defense Cloud) provide visibility into blocked and allowed lookups.

  • Clear policy groups map to compliance frameworks like NIST CSF 2.0, CMMC, HIPAA, PCI, and ISO 27002.

  • Our compliance mappings let you show auditors “this control is satisfied, here is the evidence” without reinventing the wheel.

Conclusion: Proactive, Not Reactive

Protective DNS has moved from “best practice” to baseline control. ThreatSTOP delivers the protection, intelligence, and auditability agencies and enterprises alike are being told to adopt—without adding new infrastructure or administrative burden.

With ThreatSTOP, organizations can align directly with NSA and CISA PDNS recommendations, meet compliance requirements, and most importantly, block threats before they connect.

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