HINFO Host Information Common
A legacy record type for publishing a host's CPU and operating system type — rarely used today for its original purpose.
What it's for
An HINFO (Host Information) record was originally designed, back in the early days of DNS (RFC 1035, 1987), to publish a host's CPU type and operating system — genuinely useful information in an era when the internet was a much smaller, more trusting network of research institutions, and knowing a remote host's hardware/OS combination had practical value for compatibility and administration.
Publishing this kind of information openly in DNS is now considered a bad idea from a security standpoint — it hands potential attackers free reconnaissance data about your infrastructure — so HINFO's original purpose has almost entirely fallen out of use. Where it does still show up, it's usually repurposed for something unrelated to its literal spec definition.
Format & syntax
host.example.com. 3600 IN HINFO "GENERIC-PC" "LINUX"
- CPU — a string describing the CPU/hardware type
- OS — a string describing the operating system
Both fields are free-text strings without any enforced vocabulary, though RFC 1035 references IANA-maintained lists of standard values that were more meaningful in DNS's earliest days.
How it's used in practice
- Essentially unused for its original purpose today — publishing real CPU/OS information via HINFO is now actively discouraged, since it provides reconnaissance value to attackers with no real corresponding benefit in the modern internet, where this kind of host-level detail isn't something legitimate remote parties generally need from DNS.
- Occasional repurposing (RFC 8482 style responses) — some DNS server software uses HINFO-formatted responses as a generic way to answer certain unusual query types with a minimal, non-informative response, unrelated to the record's original CPU/OS purpose — more of a protocol mechanics detail than something domain owners configure directly.
- Historical/legacy zone files — you're most likely to encounter an existing HINFO record in an older, long-maintained zone file rather than see anyone deliberately add one today for its literal documented purpose.
Common mistakes & gotchas
- Publishing real system information — if you do encounter or consider using HINFO for its original purpose, don't publish accurate details about your actual server hardware or OS — this is unnecessary reconnaissance information handed to anyone who queries it, with essentially no legitimate benefit in exchange.
- Assuming HINFO is commonly used or expected — for the vast majority of modern DNS management, there's no reason to add an HINFO record at all. Its presence in a reference doc is mostly about "know what this is if you see it in an old zone file," not "here's how to use it."
- Confusing it with TXT for general metadata — if you want to publish arbitrary text metadata about a host today, TXT is the standard, well-supported, widely understood mechanism — not HINFO, which has a narrow historical purpose and minimal modern tooling support.
Comparison & FAQ
| Type | Purpose | Key difference from HINFO |
|---|---|---|
| TXT | General-purpose arbitrary text data | The modern, widely used equivalent for publishing any kind of text metadata about a domain today |
Is HINFO still relevant for modern DNS management?
Not for its original documented purpose — publishing real hardware/OS information is considered a security anti-pattern today, since it gives attackers free reconnaissance with no offsetting benefit. It's mostly worth knowing about for recognizing legacy zone file entries.
Should I ever add an HINFO record?
Generally no, unless you have a very specific legacy or protocol-mechanics reason to. For general text metadata, TXT is the standard modern choice with far broader tooling and client support.
Why would publishing real CPU/OS info in DNS be a security risk?
It hands potential attackers free information about your infrastructure (what OS you're likely running, what vulnerabilities might apply) that they'd otherwise have to discover through other reconnaissance methods — DNS is a very public, easily queried source, so anything published there should be assumed fully public.
Does HINFO have any modern legitimate use?
Its literal documented purpose has essentially fallen out of use, though some DNS server software mechanics use HINFO-shaped responses for unrelated protocol reasons that aren't something typical domain owners configure themselves.