Why DNSSEC?
DNS answers are unsigned by default; a man-in-the-middle can spoof responses and redirect users to a fake bank site. DNSSEC adds cryptographic signatures so resolvers can verify authenticity.
Chain of Trust
Root signs .com key, .com signs yourdomain.com key, your zone signs individual records. Each level publishes DS (Delegation Signer) record in parent zone forming a trust chain down to your DNSKEY.
Implementation Steps
- Enable DNSSEC in authoritative DNS (Cloudflare one-click, or generate keys in BIND)
- Obtain DS record digest (SHA-256)
- Add DS record at registrar; they submit to upstream registry
- Wait 24 h for root zone update
Key Rollovers
KSK (Key Signing Key) rotated yearly, ZSK (Zone Signing Key) every 3 months. Use automated CDNSKEY/CDS records so parent zone pulls new DS automatically—prevents human error.
Resolver Validation
Google Public DNS and Cloudflare 1.1.1.1 validate DNSSEC by default. If signature breaks, users see NXDOMAIN or SERVFAIL instead of spoofed IP—harsh but safe.
Common Failures
- Broken DS record – mismatch digest
- Expired signatures – forgot to resign zone after TTL change
- Time skew – server clock > 5 min off causes signature mismatch
Monitoring Tools
Verisign DNSSEC Debugger, ICANN DNSSEC Test, and delv command (delv yourdomain.com +dnssec) show green “fully trusted” or red errors with line-by-line detail.
Performance Impact
Signature packets add ~400 bytes per response; negligible on modern broadband. DNSSEC does not encrypt queries (use DoT/DoH for privacy) but ensures authenticity.
TLD Support
.com, .net, .org and most new gTLDs support DNSSEC. A few ccTLDs (.tk, .ml) do not. Check before you buy if brand protection requires cryptographic assurance.
Rollback Plan
If signatures break badly, remove DS record at registrar to break chain of trust and return to insecure state. Site resolves again within minutes while you fix keys—better than prolonged outage.