RFC 9156 / START HERE
DNS name minimisation, before the details
DNS means Domain Name System. QNAME is the name being queried; minimisation means revealing less of that name in intermediate questions.
A recursive resolver can ask higher DNS servers about shorter name suffixes while finding the server responsible for the full name. It keeps the original request and later asks for the actual requested record.
The idea in one picture
Keep the full request
Reveal shorter suffixes
Ask the final question
A simplified picture of the idea; the chapters explain the actual mechanisms.
Why it exists
This November 2021 Proposed Standard replaces RFC 7816. It explains suitable query types, unknown delegation boundaries, cache and alias handling, and limits on the extra queries that minimisation can create.
A familiar example
Imagine asking which district handles a street before giving the exact house name to the final office. Intermediate offices learn less, but the helper doing all the asking still knows your complete request.
Helpful background
You can start here without reading another RFC. If these ideas are unfamiliar, these short introductions may help.
What you’ll learn next
Begin with chapter one, or choose a topic.
- Show each server only the name it needsA resolver can send shorter names to higher servers while still keeping the original request.→
- Find delegation cuts and restore the original queryThe published cold-cache sequence probes labels before asking for the requested mail records.→
- Handle cache, absence, aliases and retriesDifferent reply categories cause different transitions; an alias at a probe is not the original answer.→
- Choose the query type and the correct delegation sideA selected probe type is independent of the incoming type, and DS belongs on the parent side.→
- Bound extra work and keep the privacy limits visibleLimit label-driven probes, reuse knowledge and distinguish minimisation from encryption.→
This introduction explains RFC 9156 (2021). Read the original RFC ↗