Domain Name System Security Extensions (DNSSEC)

DNSSEC adds digital signatures to DNS records, ensuring:

  • Authenticity – The response actually came from the legitimate DNS server.

  • Integrity – The data wasn’t tampered with in transit.

  • Non-repudiation – The owner of the domain really published those records.

Without DNSSEC, DNS is vulnerable to:

  • Cache poisoning – Attackers inject fake DNS records (like sending you to a scam bank site).

  • Man-in-the-middle (MITM) attacks – Intercepting and altering DNS responses.

  • DNS spoofing – Tricking systems into trusting malicious servers.

How DNSSEC works (without making your brain melt)

Signing the records: The cryptographic seal of approval

  • The domain owner generates public/private key pairs for their DNS zone.

  • Each DNS record (A, AAAA, MX, etc.) gets a digital signature (RRSIG).

  • These signatures are stored alongside the records in the DNS zone.

The chain of trust

From root to your domain DNSSEC works like a hierarchical notary system:

  • Root Zone (.) signs the Top-Level Domains (TLDs) (.com, .net, etc.).

  • TLDs sign the domains under them (e.g., example.com).

  • Your domain signs its subdomains (mail.example.com, www.example.com).

If any link in this chain is broken, validation fails.

Checking the signatures

When a resolver (like your ISP or Google’s 8.8.8.8) gets a DNS response:

  • It fetches the public key (DNSKEY) for the domain.

  • It verifies the signature (RRSIG) against the data.

  • If everything checks out, the record is trusted. If not? Warning signs go up.

The ugly truth: DNSSEC’s challenges

  1. Deployment is Still Patchy

    • Many domains still don’t use DNSSEC (looking at you, facebook.com).

    • Some registrars make it unnecessarily hard to enable.

  2. Complexity = Misconfigurations Galore

    • Key rollovers must be timed perfectly—or the domain breaks.

    • Human error (expired keys, bad signatures) can cause outages.

  3. DNSSEC signs records but doesn’t hide them. For privacy, you still need DNS-over-HTTPS (DoH) and DNS-over-TLS (DoT)

Should you use DNSSEC?

Yes, if:

  • You run a high-value domain (banking, government, corporate).

  • You want to prevent DNS hijacking & spoofing.

  • You’re okay with extra maintenance (key management).

No, if:

  • Your registrar doesn’t support it (check first!).

  • You’re not prepared to monitor key expirations.

  • You think “DNS troubleshooting” sounds like a nightmare.


Last update: 2025-06-11 07:09