DNSLink Gateway Specification

2.1.1 Host (request header)

Defines the DNSLink name to RECURSIVELY resolve into an immutable /ipfs/{cid}/ prefix that should be prepended to the path before the final IPFS content path resolution is performed.

Implementations MUST ensure DNSLink resolution is safe and correct:

• each DNSLink may include an additional path segment, which MUST be preserved
• each DNSLink may point at other DNSLink, which means there MUST be a hard recursion limit (e.g. 32) and HTTP 400 Bad Request error MUST be returned when the limit is reached.

Example: resolving an advanced DNSLink chain

To illustrate, given DNSLink records:

• _dnslink.a.example.com TXT record: dnslink=/ipns/b.example.net/path-b
• _dnslink.b.example.net TXT record: dnslink=/ipfs/bafy…qy3k/path-c

HTTP client sends GET /path-a request with Host: a.example.com header which recursively resolves all DNSLinks and produces the final immutable content path:

1. Host header + /path-a → /ipns/a.example.net/path-a
2. Resolving DNSlink at a.example.net replaces /ipns/a.example.net with /ipns/b.example.net/path-b
3. Resolving DNSlink at b.example.net replaces /ipns/b.example.net with /ipfs/bafy…qy3k/path-c
4. The immutable content path is /ipfs/bafy…qy3k/path-c/path-b/path-a