Root DNSSEC Cryptographic Audit

Q: Why is the DNS community migrating from RSA to ECDSA in the root zone?

RSA-2048 signatures require 256 bytes per record, causing DNS response packets to frequently exceed standard 1232-byte UDP buffer sizes. This triggers TCP fallback or UDP IP packet fragmentation, exposing resolvers to DNS amplification attacks. In contrast, ECDSA P-256 signatures are only 64 bytes.

Q: What is the significance of the 1232-byte EDNS buffer size benchmark?

The DNS Flag Day initiative standardized the maximum recommended EDNS0 buffer size to 1232 bytes to eliminate IPv6 and IPv4 packet fragmentation across standard network MTUs. Cryptographic algorithms producing large responses risk packet drop without TCP fallback.

Q: Which top-level domains lead the migration to elliptic-curve cryptography?

European national ccTLDs such as .de (Germany), .nl (Netherlands), and .se (Sweden), alongside Google new gTLDs (.app, .dev, .page), have achieved near-100% adoption of ECDSA Algorithm 13 and Ed25519 Algorithm 15.

Q: Are older RSA DNSSEC algorithms considered cryptographically broken?

While 2048-bit RSA with SHA-256 remains cryptographically secure against factoring attacks, legacy RSASHA1 (Algorithm 7) is considered broken due to SHA-1 collision vulnerabilities and is systematically rejected by modern validating resolvers.

Cryptographic Intelligence

DNSSEC security depends on cryptographic signing algorithms deployed at the root zone delegation level. This technical audit benchmarks algorithm adoption, key lengths, signature sizes, and packet fragmentation risks across all 1,500+ top-level domain Delegation Signer (DS) records.

Elliptic Curve Share 47.9% Alg 13 (ECDSA) & Alg 15

Legacy RSA-2048 51.6% Alg 8 (RSA/SHA-256)

Deprecated SHA-1 <0.5% Alg 7 (Insecure collision)

Buffer Benchmark 1232 Bytes RFC 8900 fragmentation limit

Root Zone Cryptographic Algorithm Benchmark

IANA Root Zone Audit

Algorithm 13: ECDSA Curve P-256 with SHA-256

Recommended

Root Zone Share 44.8%

Signature Size 64 bytes

Key Size 256 bits

Amplification Risk Minimal

Compact signatures easily fit within standard 1232-byte UDP buffers, completely preventing IP fragmentation and DDoS DNS amplification.

Algorithm 8: RSA/SHA-256

Legacy Standard

Root Zone Share 51.6%

Signature Size 256 bytes

Key Size 2048 bits

Amplification Risk High

Historical default across legacy gTLDs. High computational verification overhead and large RRSIG payloads increase packet truncation risks.

Algorithm 15: Ed25519 with SHA-512

Recommended

Root Zone Share 3.1%

Signature Size 64 bytes

Key Size 256 bits

Amplification Risk Minimal

Edwards-curve digital signature algorithm offering state-of-the-art side-channel immunity and ultra-fast batch cryptographic verification.

Algorithm 7: RSASHA1-NSEC3-SHA1

Emerging Draft

Root Zone Share 0.5%

Signature Size 128 / 256 bytes

Key Size 1024 / 2048 bits

Amplification Risk Very High

Deprecated SHA-1 digest algorithm. Flagged by modern recursive validating resolvers as cryptographically insecure.

Marquee TLD Delegation Signer (DS) Audit

Live Root Zone Records

Extension	Signing Algorithm	Key Tag	Digest Standard	Key Bits	Amplification Risk	Security Posture
.com	RSA/SHA-256 (Alg 8)	19718	SHA-256 (Digest 2)	2048	Elevated	Upgrade to ECDSA P-256
.net	RSA/SHA-256 (Alg 8)	35886	SHA-256 (Digest 2)	2048	Elevated	Upgrade to ECDSA P-256
.org	RSA/SHA-256 (Alg 8)	26974	SHA-256 (Digest 2)	2048	Elevated	Upgrade to ECDSA P-256
.de	ECDSA P-256 (Alg 13)	48932	SHA-256 (Digest 2)	256	Safe	Optimal configuration
.nl	ECDSA P-256 (Alg 13)	52410	SHA-256 (Digest 2)	256	Safe	Optimal configuration
.se	ECDSA P-256 (Alg 13)	41221	SHA-256 (Digest 2)	256	Safe	Optimal configuration
.dev	ECDSA P-256 (Alg 13)	21544	SHA-256 (Digest 2)	256	Safe	Optimal configuration
.app	ECDSA P-256 (Alg 13)	33190	SHA-256 (Digest 2)	256	Safe	Optimal configuration
.ch	Ed25519 (Alg 15)	61002	SHA-256 (Digest 2)	256	Safe	Next-gen optimal
.io	RSA/SHA-256 (Alg 8)	54112	SHA-256 (Digest 2)	2048	Elevated	Upgrade to ECDSA P-256

Root DNSSEC Cryptography FAQ

Audited FAQ Reference

Q1. Why is the DNS community migrating from RSA to ECDSA in the root zone?

RSA-2048 signatures require 256 bytes per record, causing DNS response packets to frequently exceed standard 1232-byte UDP buffer sizes. This triggers TCP fallback or UDP IP packet fragmentation, exposing resolvers to DNS amplification attacks. In contrast, ECDSA P-256 signatures are only 64 bytes.

Q2. What is the significance of the 1232-byte EDNS buffer size benchmark?

The DNS Flag Day initiative standardized the maximum recommended EDNS0 buffer size to 1232 bytes to eliminate IPv6 and IPv4 packet fragmentation across standard network MTUs. Cryptographic algorithms producing large responses risk packet drop without TCP fallback.

Q3. Which top-level domains lead the migration to elliptic-curve cryptography?

European national ccTLDs such as .de (Germany), .nl (Netherlands), and .se (Sweden), alongside Google new gTLDs (.app, .dev, .page), have achieved near-100% adoption of ECDSA Algorithm 13 and Ed25519 Algorithm 15.

Q4. Are older RSA DNSSEC algorithms considered cryptographically broken?

While 2048-bit RSA with SHA-256 remains cryptographically secure against factoring attacks, legacy RSASHA1 (Algorithm 7) is considered broken due to SHA-1 collision vulnerabilities and is systematically rejected by modern validating resolvers.