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SVCB · type 64

Generic service binding; HTTPS is its web flavour.

Last updated 5 Oct 2026 from the IANA RR TYPE registry

Short answer

SVCB records describe how to reach a service at a name: target host, priority and parameters such as protocols and ports. The HTTPS type is SVCB specialised for the web; other protocols define their own use, for example DNS over HTTPS and DNS over TLS resolver discovery (RFC 9461, RFC 9462).

Type
SVCB
Code
64
Defined in
RFC 9460
IANA description
General-purpose service binding
Field: Priority
0 alias, 1+ service
Field: Target
Host providing the service
Field: Parameters
Key=value list

How it works

For most domain owners SVCB matters only through HTTPS records their CDN publishes.

Example

_dns.resolver.example.  300  IN  SVCB  1 doh.resolver.example. alpn=h2 dohpath=/dns-query{?dns}

Example uses reserved documentation names and addresses (RFC 2606, RFC 5737, RFC 3849).

Common mistakes

  • Expecting clients to use SVCB for a protocol that hasn’t defined how.

How to check yours

The record has two modes. In alias mode (priority 0) it points the name elsewhere, like a CNAME that is allowed at the zone apex. In service mode (priority 1 or higher) it carries the connection parameters directly. Clients pick the lowest priority they support and ignore parameters they don’t understand.

Related record types

HTTPSTells browsers how to connect: HTTP/3, alternative endpoints, ECH.SRVLocates a service: host, port, priority and weight.

Sources

Sources

  1. IANA: Resource Record (RR) TYPEs registry · checked 5 Oct 2026
  2. RFC 9460 · checked 5 Oct 2026