6.11 Conformance

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A conforming implementation MUST satisfy every requirement in this chapter. This section collects them by role.

6.11.1 Resolver obligations #

6.11.1.1 Doors #

  1. Offer the native socket, the stub listener and answer the shim, and run one resolution function behind all three (§6.3).
  2. Offer no other policy path: no files, no in-shim DNS, no fallback (§6.3).

6.11.1.2 Native channel #

  1. Frame as §6.4; refuse an oversized request without reading it, with an error reply (§6.4).
  2. Ignore unknown keys; reject duplicate keys (§6.4).
  3. One request per connection; bound the time a request may take to arrive (§6.4).
  4. Access-check every request against the control object with the peer's real token; default Everyone RESOLVER_QUERY, SYSTEM and Administrators all (§6.4).
  5. Answer unknown requests and denied requests with error replies (§6.4, §6.5).

6.11.1.3 Outcomes #

  1. Never report unavailable as notfound; never cache unavailable (§6.6).
  2. Report unvalidated until validating; never forward an upstream's AD (§6.6).

6.11.1.4 Resolution #

  1. Route every question to exactly one scope, in the order of §6.7; never fan out.
  2. Honour an exclusive scope absolutely while it is up (§6.7).
  3. Expand single labels with applicable domains only; never send one bare; never expand a multi-label name; no ndots (§6.7).
  4. Answer the synthetic names of §6.7 before any network; never forward .local; never speak LLMNR.
  5. Key the cache by scope; flush a scope whose servers change or that goes away; cap TTLs as §6.A2 (§6.7).
  6. Fresh source port, random identifier, 0x20 case with exact echo; ignore mismatched replies (§6.7).
  7. EDNS0 with the §6.A2 buffer; TCP on truncation; demote failing servers; bounded attempts (§6.7).

6.11.1.5 Stub door #

  1. Listen on 127.0.0.53 only, UDP and TCP; ignore non-loopback sources (§6.8).
  2. Render outcomes as §6.8; CNAME from a bare question to its expanded name; NOTIMP and FORMERR as §6.8; truncate over the buffer.
  3. Bind without privilege (§6.8).

6.11.1.6 Network manager channel #

  1. Subscribe; replace scopes on every snapshot; reconnect with backoff; keep answering while disconnected (§6.9).
  2. Read only Machine\System\Network\Resolver from the registry (§6.9).

6.11.2 Network manager obligations #

  1. Answer subscribe with a snapshot and stream one on every change on the same connection (§6.9).
  2. Send whole snapshots, never deltas; merge profile and lease facts itself (§6.9).

6.11.3 Client obligations #

  1. Treat an error reply as "not answered", never as notfound (§6.5).
  2. Be written against validation (§6.6).

6.11.4 Shim obligations #

  1. One connection per libc call; answer localhost alone; UNAVAIL when the resolver is unreachable; ERANGE retry (§6.10).
  2. No files, no DNS, no cache (§6.10).
  3. Map outcomes as §6.10; never render unavailable as NOTFOUND.

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