nic-6443 commented on issue #10956:
URL: https://github.com/apache/apisix/issues/10956#issuecomment-4676893100

   The 2s gap in your logs sits exactly across the in-request DNS lookup 
(between `http_access_phase` and `dns_parse`), so this looks like the 
configured DNS resolver taking ~2s to answer — typically a timeout-and-retry 
against a slow or lossy nameserver — rather than APISIX Lua code being slow. 
When upstream nodes are domain names, APISIX resolves them synchronously in the 
access phase once the cached record's TTL expires, so any resolver hiccup 
surfaces directly as request latency.
   
   Worth checking the resolvers APISIX picked up (config.yaml / resolv.conf), 
running a local caching resolver next to APISIX, or setting 
`apisix.dns_resolver_valid` to pin TTLs; using IP nodes or a discovery module 
avoids the inline lookup entirely. Recent versions also upgraded the bundled 
DNS client to lua-resty-dns-client 7.1.0 (#12851, since 3.15.0). Since this is 
two years old, environment-specific and marked can't-reproduce, I'd suggest 
closing it — happy to dig in again if anyone can reproduce on a current version 
with resolver details.
   


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