DNS PKI SECURITY CHECKER

CAA Record Checker – Validate DNS CAA Records Online

Lookup and audit DNS Certification Authority Authorization (CAA) resource records in real time. Verify authorized Certificate Authorities, wildcard issuance policies, and incident violation reporting URIs.

RFC 8659 Standard Compliant

Real-Time Authoritative Lookup

Non-Intrusive DNS Query

Zero Account Required

ℹ️ Scope & Limitation Notice: Queries public authoritative DNS servers; cannot verify internal intranet split-horizon DNS records.

Launch Tool How It Works & Guide

CAA Certificate Policy Flow

RFC 8659 DNS PKI

1 Domain Input

Sanitized FQDN query target

2 DNS CAA Query

Type 257 resource record lookup

3 Directive Parsing

issue, issuewild & iodef tags

4 CA Authorization Matrix

Permitted Certificate Authorities

Mode: Authoritative DNS Query Sample Preview

Check a Domain's CAA Records

RFC 8659 Tree Walking Engine

Enter a public domain to retrieve and analyze its effective CAA certificate-issuance policy.

FUNCTIONAL ARCHITECTURE

What Does the CAA Record Checker Do?

The CAA Record Checker inspects a domain DNS Certification Authority Authorization (CAA) records (Type 257) to verify which Certificate Authorities are legally permitted to issue SSL/TLS certificates for that domain and its subdomains.

Mandated by the CA/Browser Forum since September 2017, CAA records prevent attackers and unauthorized internal teams from procuring fraudulent or rogue TLS certificates from unapproved commercial Certificate Authorities.

STEP-BY-STEP METHODOLOGY

How the CAA Record Checker Works

Resolve Domain CAA Records

Queries authoritative DNS name servers for Type 257 (CAA) resource records.

Evaluate Parent Tree Fallback

If no CAA record exists at the sub-domain level, checks parent domain records according to RFC 8659 inheritance rules.

Parse Directives & Tags

Extracts "issue" (standard certs), "issuewild" (wildcard certs), and "iodef" (security violation reporting endpoints).

Audit Configuration Posture

Flags missing CAA records, wildcard issuance vulnerabilities, and unmonitored incident reporting configurations.

GEO Methodology Declaration: This tool performs live DNS Type 257 resource record lookups adhering strictly to RFC 8659 specifications via authoritative name server resolution.

DECISION MATRIX

How to Interpret CAA Record Checker Results

Result / Status	Technical Meaning	Recommended Action
Configured & Restrictive	Specific CAs authorized (e.g., letsencrypt.org, digicert.com) with active iodef reporting.	Maintain configuration; ensure incident contact email or webhook in iodef remains active.
Permissive / No CAA Record	Any publicly trusted Certificate Authority worldwide may issue certificates for this domain.	Create a CAA record in your DNS zone to restrict issuance to your preferred CAs.
Wildcards Unrestricted	"issue" tag configured without explicit "issuewild", allowing authorized CAs to issue broad wildcard certificates.	Add "issuewild" directive or set it to ";" to explicitly prohibit wildcard certificate generation.
Issuance Prohibited (";")	Explicit policy prohibiting all certificate issuance (tag value set to ";").	Intended only for parked or non-web domains where no certificates should ever be issued.

TECHNICAL FOUNDATION

RFC 8659 Directive Hierarchy and the Critical Role of iodef

Under RFC 8659 (which obsoleted RFC 6844), CAs must check CAA records prior to certificate issuance. The three standard properties are: issue (authorizes specific CA for non-wildcard certs), issuewild (authorizes specific CA for wildcard certs; overrides "issue" for wildcards), and iodef (Incident Object Description Exchange Format URI).

When an unauthorized entity requests a certificate for a domain with an active CAA policy, compliant CAs must reject the request and dispatch an automated incident report to the URI specified in the iodef tag (such as mailto:[email protected] or an HTTPS webhook), providing immediate early warning of potential compromise attempts.

OPERATIONAL PRACTICES

Real-World Use Cases for CAA Record Checker

Security Operations (SecOps)

Detect Unauthorized Certificate Requests

Configuring iodef reporting to catch rogue certificate generation attempts and domain hijacking.

Infrastructure Engineers

Consolidate Enterprise PKI Vendors

Restricting certificate issuance across corporate domains to single approved vendors (e.g., DigiCert, Sectigo).

DevOps Administrators

Allow Automated ACME Issuance

Authorizing Let Encrypt or Cloudflare while preventing manual shadow-IT certificate generation.

Compliance Auditors

Verify PKI Governance Controls

Auditing external domain perimeters to confirm that shadow TLS certificates cannot be provisioned.

TRANSPARENT BOUNDARIES

Limitations of the CAA Record Checker

Maintaining an accurate threat model requires understanding what external point-in-time tools can and cannot evaluate:

⚠️ CAA records control public Certificate Authority issuance; they cannot prevent internal private enterprise CAs installed in private trust stores.
⚠️ DNS caching and propagation delays (TTL) mean recent DNS updates may take minutes or hours to reflect across all global resolvers.
⚠️ A misconfigured CAA record that excludes your own hosting provider automated CA can cause automated TLS renewals to fail, leading to expired certificate outages.

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EXPERT FAQS

Frequently Asked Questions: CAA Record Checker

What is a DNS CAA record? +

A Certification Authority Authorization (CAA) record is a DNS resource record (Type 257) that specifies which Certificate Authorities (CAs) are allowed to issue SSL/TLS certificates for a domain.

Is having a CAA record mandatory? +

Creating a CAA record is optional for domain owners, but checking CAA records is mandatory for all publicly trusted Certificate Authorities under CA/Browser Forum Baseline Requirements.

What happens if a domain has no CAA record? +

If no CAA record exists on the domain or any of its parent domains, any publicly trusted Certificate Authority in the world is permitted to issue a certificate for that domain.

How do I prevent wildcard certificates using CAA? +

Add a CAA record with the tag "issuewild" and value ";" (e.g., example.com. IN CAA 0 issuewild ";"). This permits standard certificates under "issue" while strictly prohibiting wildcard issuance.

Can CAA protect against compromised Certificate Authorities? +

If a rogue or compromised CA intentionally ignores CA/Browser Forum rules, CAA cannot block issuance. However, Certificate Transparency (CT) logging will expose the violation for immediate revocation.

PRIMARY REFERENCES

Authoritative Standards & Technical References

This tool operates in direct accordance with verified cybersecurity standards and technical specifications established by authoritative primary institutions:

IETF / RFC Editor

RFC 8659: DNS Certification Authority Authorization (CAA)

The definitive engineering standard for CAA resource records and CA processing requirements.

CA/Browser Forum

CA/Browser Forum Baseline Requirements

Mandates compulsory CAA record verification across all publicly trusted Certificate Authorities.

Cybersecurity Navigation & Assessment Hub

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