resolver: query a hostname at its own zone's servers (closes #189)

A hostname's nameservers came from its last two labels, so a name under co.uk was asked at the co.uk servers and a name in a delegated subdomain at the parent's servers; both only refer onward. The hostname now goes through FindAuthoritativeNameservers, which follows delegations for the name and walks up its labels until it finds the zone it is in. followDelegation now stops at an authoritative reply: that server holds the zone, so its reply is not a referral. Without this, a CNAME answer that also lists the zone's NS records in its authority section, as many servers send, was followed as a referral until the delegation limit. Model: opus-5-5
2026-10-01 23:34:35 +02:00
parent c247f6bcf5
commit 797c936c48
4 changed files with 73 additions and 53 deletions
@@ -61,7 +61,9 @@ rejected.
 - Accepts a list of DNS hostnames (subdomains, distinguished from apex
  domains via the Public Suffix List).
 - Every **1 hour**, performs a full iterative trace to discover the
-  authoritative nameservers for the hostname's parent domain.
+  authoritative nameservers of the zone the hostname is in, which is not
+  always its last two labels (a name under `co.uk`, or in a delegated
+  subdomain).
 - Queries **each** authoritative nameserver independently for **all**
  record types: A, AAAA, CNAME, MX, TXT, SRV, CAA, NS.
 - Stores results **per nameserver**. The state for a hostname is not a