What changed
Cloudflare's 1.1.1.1 resolver now validates DNSSEC signatures using ML-DSA-44, the NIST-standardized post-quantum signature algorithm assigned DNSSEC algorithm number 18. ML-DSA-44 signatures are 2,420 bytes and public keys are 1,312 bytes, so signed DNS responses can exceed normal UDP budgets and trigger TCP or other transport fallback. During the transition, zones may publish both conventional and post-quantum signatures. Cloudflare applies a stricter local validation policy when an authenticated parent DS record indicates ML-DSA-44 support, requiring a valid post-quantum path instead of accepting a forgeable conventional path as a downgrade. This is resolver-side support, not a complete post-quantum DNSSEC chain; authoritative servers, registrars, registries and eventually the root still need compatible deployment.
Why it matters
TLS is not the only public-key system that quantum migration will touch. DNSSEC underpins authenticity for signed DNS records, and its migration has harder operational constraints because much larger signatures must pass through old network assumptions and because compatibility with older resolvers can undermine post-quantum security. Turning validation on in a resolver as large as 1.1.1.1 creates real-world evidence about bandwidth, TCP fallback, verification cost and broken middleboxes years before a quantum-safe chain is required everywhere.
ML-DSA-44 is much larger than current DNSSEC signatures
Cloudflare compares the 2,420-byte ML-DSA-44 signature with 64-byte ECDSA P-256 signatures. The post-quantum signature alone exceeds common DNS-over-UDP payload budgets, so resolvers and authoritative servers must handle truncation and retries without assuming DNS fits into a small datagram.
Dual-signing creates a downgrade problem
A transition cannot immediately remove conventional algorithms because older resolvers need them. But once a conventional signature algorithm becomes breakable, a resolver that accepts any valid path could be tricked into accepting a forged old-algorithm answer even though a post-quantum signature also exists.
1.1.1.1 enforces a stronger local rule when PQ support is authenticated
Cloudflare uses DS records in the parent zone as the authenticated signal. When that chain says ML-DSA-44 should be present, 1.1.1.1 requires at least one valid post-quantum validation path rather than allowing a conventional path to satisfy validation by itself.
Resolver support is only the first deployment layer
A fully post-quantum DNSSEC chain also needs authoritative DNS software to sign with ML-DSA-44, registrars to submit the corresponding DS records, registries to publish them and eventually the DNS root to carry a post-quantum trust anchor.
Large-scale testing now can expose operational failures early
Cloudflare plans to measure verification cost, bandwidth and additional TCP use and to run background probes against post-quantum-signed test domains. The practical value today is discovering network and software assumptions before a future cryptographic emergency forces a rushed migration.