What is Protective DNS (PDNS)?
Protective DNS (often referred to as PDNS) is a DNS-layer security service that blocks or redirects DNS queries to malicious, suspicious, or policy-violating domains before a connection is ever made. It works as an early barrier against malware, phishing, ransomware, and command-and-control (C2) infrastructure.
PDNS is a functional category that describes a set of DNS-layer security capabilities rather than a specific product. However, various security providers offer PDNS-compliant services or solutions that deliver these capabilities like: blocking malicious domains, applying threat intelligence, and enforcing security policies via DNS resolution.
Governments have increasingly backed the use of PDNS. In 2021, the National Security Agency (NSA) and the Cybersecurity and Infrastructure Security Agency (CISA) issued joint guidance advocating for the adoption of protective DNS, recognizing its role in national and organizational cybersecurity resilience.
How Protective DNS Works
When a user initiates a DNS query, a protective DNS service inspects the request in real time, checking the domain against multiple data sources including:
- Threat intelligence databases
- Machine learning models that detect emerging threats
- Content categorization databases
If the domain is deemed safe, the query resolves normally. If it is identified as malicious or high risk, the service either blocks the resolution or redirects it to a safe page or sinkhole.
This process is typically passive, quick, and requires no end-user interaction, making it a zero-friction defense layer.
Why is Protective DNS Important?
DNS is essential to the Internet’s function, and because it is so pervasive, it is frequently exploited by attackers. Threats like phishing, malware, and C2 communications often depend on DNS queries to locate malicious servers or transmit data.
Protective DNS is particularly valuable in:
- Hybrid work environments
- Bring-your-own-device (BYOD) scenarios
- Remote and distributed workforces
- IoT and unmanaged device ecosystems
PDNS reduces reliance on perimeter-based defenses like firewalls, which are less effective in decentralized environments.
Additionally, human error remains a persistent vulnerability. Even users with high security awareness may click malicious links or be tricked by well-crafted phishing attempts. Protective DNS provides a protective barrier before these threats can connect.
How to Implement PDNS
Protective DNS can be implemented via:
- Secure resolvers configured at the network or endpoint level
- Filtering agents installed on devices
- Cloud-managed DNS security platforms
Deployment is typically quick and non-disruptive, making it scalable across devices and networks.
How to Choose a PDNS Provider
When selecting a PDNS service provider, organizations should look for offerings that align with NSA and CISA recommendations. These include features like:
- Malicious activity alerts
- Enterprise dashboard views
- Historical logging and analysis
- High availability to ensure uninterrupted DNS resolution
Who Uses Protective DNS?
- IT and security teams implementing Zero Trust strategies
- Managed Service Providers (MSPs) and Managed Security Service Providers (MSSPs) protecting hybrid and remote clients
- Government agencies adhering to CISA mandates
- Highly regulated sectors such as healthcare and finance
- Remote-first companies securing off-network devices
Protective DNS vs Other DNS Security Layers
|
DNS Layer |
Function |
Notes |
| Basic DNS |
Resolves domain names to IP addresses |
No built-in security |
| DNSSEC |
Authenticates DNS responses |
Ensures validity, not safety |
| DNS Filtering |
Blocks domains based on threat or content |
Often overlaps with PDNS |
| PDNS |
Applies threat intelligence at DNS level |
May include filtering, analytics, AI-driven detection |
| Encrypted DNS (DoH/DoT) |
Encrypts DNS queries in transit |
Enhances privacy, not filtering |
PDNS solutions often combine the benefits of DNS filtering, DNSSEC validation, and advanced threat analytics, delivering broader protection than any single DNS security layer.
Did you know? DNSFilter operates as both a PDNS provider and a DNS filtering solution, combining real-time AI-based domain classification with robust policy enforcement.
Examples of Protective DNS
- A healthcare organization uses PDNS to block ransomware domains, reducing the risk of operational disruptions.
- A remote-first company secures employee devices on home and public networks with PDNS agents.
- Government agencies adopt PDNS following CISA guidance to protect federal infrastructure from DNS-based threats.
To see how organizations apply Protective DNS in practice, explore our Protective DNS use cases.
Related Terms
- DNS: The foundational system for translating domain names into IP addresses.
- DNSSEC: Verifies the authenticity of DNS responses to prevent tampering.
- PDNS (Protective DNS): A security strategy that combines DNS resolution with threat intelligence to detect and prevent cyberattacks.
- DNS over TLS (DoT): Encrypts DNS traffic to enhance privacy.
- DNS over HTTPS (DoH): Encrypts DNS queries within HTTPS connections.
- DNS Poisoning: An attack technique where false DNS information is inserted into a resolver’s cache.
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