resolver: a nameserver is asked at each of its addresses in turn (closes #285)

A nameserver's queries went only to the first IPv4 address its name resolves to, so one unreachable address made it fail whenever that address came first in the answer. Each record type is now asked at the addresses one at a time until one gives a usable reply, and the next type is asked first at the address that gave it. The README's DNS Resolution Strategy says which addresses are asked. Model: opus-5-5
2026-10-15 10:17:14 +00:00
parent b79726acc6
commit 623e7b2c69
5 changed files with 130 additions and 33 deletions
@@ -19,6 +19,8 @@ milestone: https://git.eeqj.de/sneak/dnswatcher/milestone/7

 # Completed Steps

+- 2026-10-15: a nameserver is asked at each of its IPv4 addresses in turn, so it
+  has failed only when none of them gives a usable reply (closes #285).
 - 2026-10-13: a hostname or a domain whose zone's nameservers all stop answering
  gets an NS Failure for each, then an NS Recovery (closes #284).
 - 2026-10-13: an IPv6 address is written in brackets before its port, as in