HINFO record

hinfo.dns.netmeister.org. 3600 IN HINFO "PDP-11" "UNIX"
  ; CPU "PDP-11", OS "UNIX"

cloudflare.com. 3600 IN HINFO "RFC8482" ""
  ; minimal answer to an ANY query (RFC 8482), not real host data

github.com. 786 IN HINFO "RFC8482" ""
  ; minimal answer to an ANY query (RFC 8482), not real host data

discord.com. 3600 IN HINFO "RFC8482" ""
  ; minimal answer to an ANY query (RFC 8482), not real host data

What the HINFO record does

RFC 1035 intended HINFO for things like "VAX-11/780" "UNIX". Publishing hardware and OS details helps attackers more than anyone else, so it fell out of use.

ANY queries were widely abused for amplification attacks. RFC 8482 lets a server answer ANY with a small synthesised RRset instead of everything at the name, and recommends HINFO with the CPU field RFC8482 and an empty OS field. Cloudflare-hosted zones answer this way, which the live examples show.

Zone-file syntax

host.example.com.  3600  IN  HINFO  "PDP-11" "UNIX"
example.com.       3600  IN  HINFO  "RFC8482" ""   ; minimal ANY response

Wire format: RDATA is two character-strings: CPU and OS.

Fields

Field	Meaning
CPU	Hardware type, free text.
OS	Operating system, free text.

Common mistakes

• Publishing real hardware or OS versions on internet-facing hosts.
• Treating an HINFO "RFC8482" answer to ANY as the full record set; query each type you need.

Specification

• RFC 1035: Domain names - implementation and specification
• RFC 8482: Providing Minimal-Sized Responses to DNS Queries That Have QTYPE=ANY

Related record types

• LOC: geographic location of a host
• TXT: free-form text for verification and policy
• SOA: serial, timers and negative caching

All DNS record types