Advanced DNSSEC Checker

A DNSSEC Validation Failed error, often resulting in a SERVFAIL response, indicates that the DNS resolver could not verify the digital signature (RRSIG) of the requested record.

This can happen for several reasons:

• Missing or Incorrect DS Record: The parent zone has a DS record that doesn't match the child zone's DNSKEY.
• Expired RRSIG: The signatures on your records have expired and haven't been re-signed.
• Clock Skew: Significant time differences between the resolver and the authoritative server.
• Algorithm Mismatch: Using a cryptographic algorithm not supported by the resolver.

A BOGUS status means the chain of trust is broken. To fix this, you must identify where the break occurred.

Steps to resolve:

1. Verify DS Records: Log in to your domain registrar and ensure the DS record matches the KSK (Key Signing Key) in your DNS zone. This is the most common issue.
2. Check Signature Expiry: Ensure your zone is being signed regularly. RRSIGs have validity periods.
3. Validate Glue Records: Ensure glue records for your nameservers are correct.

Reference: RFC 4033 - DNS Security Introduction

SERVFAIL is a generic "Server Failure" error, but for DNSSEC-signed domains, it typically means validation failure.

Validating resolvers (like Google DNS 8.8.8.8 or Cloudflare 1.1.1.1) will return SERVFAIL if they suspect the data has been tampered with or if the configuration is broken (BOGUS). Non-validating resolvers might still return the IP address, leading to inconsistent user experiences.

Tip: Use a tool like dig +cd example.com (Checking Disabled) to see if you get an answer. If you do, it's definitely a DNSSEC validation issue.

The Chain of Trust is a sequence of cryptographic validations starting from the Root Zone (.) down to your specific domain.

• The Root Zone signs the TLD (e.g., .com) keys.
• The TLD (Detailed via DS records) signs the keys for your domain (e.g., example.com).
• Your domain signs its own records (A, MX, CNAME, etc.).

If any link in this chain is broken (e.g., missing DS record at the registrar), the entire trust chain collapses, and the domain becomes "Insecure" or "Bogus".

Every DNSSEC signature (RRSIG) has a valid start and end time. If the signature expires, validating resolvers will treat the data as invalid (BOGUS) and return SERVFAIL to protect users from potentially replayed old data.

Solution: Ensure your DNS provider handles automatic re-signing of your zone. If you manage your own BIND or KNOT server, automate the signing process using cron jobs or tools like OpenDNSSEC.

A "Missing DS Record" error means the parent zone (e.g., the .com registry) does not have the Delegation Signer record for your domain. Without this, the chain of trust cannot be established from the parent to your child zone.

Fix:
1. Go to your DNS Hosting provider and get your public KSK (Key Signing Key) Digest.
2. Log in to your Domain Registrar (where you bought the domain).
3. Look for "DNSSEC" or "DS Records" in the management settings.
4. Add the DS record details provided by your DNS host.

DNSSEC typically uses two keys to separate roles and simplify key management:

• KSK (Key Signing Key): Only signs the DNSKEY record set. It is the key referenced by the DS record in the parent zone. It is changed (rolled over) less frequently.
• ZSK (Zone Signing Key): Signs all other records in the zone (A, MX, etc.). It can be rolled over easily without coordinating with the parent registrar.

Minimally. DNSSEC adds digital signatures to DNS responses, making the packets larger.

This can occasionally cause:

• Switching from UDP to TCP if the packet size exceeds the limit (fragmentation).
• Slight increase in DNS resolution time (milliseconds) due to validation processing on the resolver side.

However, once cached, there is zero impact on page load speed. The security benefits far outweigh the negligible latency during the initial lookup.