Slow queries overall when upstream to local domain should be returning NXDOMAIN but timeouts instead

[felipejfc]

Prerequisites

• I have checked the Wiki and Discussions and found no answer

• I have searched other issues and found no duplicates

• I want to report a bug and not ask a question or ask for help

• I have set up AdGuard Home correctly and configured clients to use it. (Use the Discussions for help with installing and configuring clients.)

Platform (OS and CPU architecture)

Linux, AMD64 (aka x86_64)

Installation

Docker

Setup

On one machine

AdGuard Home version

edge

Action

When I setup an upstream to my local domain:
[/local/]10.0.0.1 //which is an UDM PRO router
If some machine in the network is, for some reason, looking for names that don't exist, e.g. iPhone.local, adguard home will keep timing out when trying to resolve this name on upstream router, these requests build up and slow down everything else.
If I try to manually nslookup iPhone.local 10.0.0.1 from my PC, the upstream answers instantaneously with NXDOMAIN. I wonder why on adguard these requests are timing out instead.

Expected result

No slowlyness, when adguard home calls upstream to resolve a local domain that doesn't exist it should fail fast.

Actual result

Instead of failing fast I'm hitting timeouts as observed in the logs, e.g.:

2024/04/28 01:50:12.395395 [error] dnsproxy: upstream 10.0.0.1:53 failed to exchange ;aee03874-2f62-4298-9eb3-3a29536aa4bf.local.      IN       AAAA in 20.001546624s: exchanging with 10.0.0.1:53 over udp: read udp 10.0.0.51:39870->10.0.0.1:53: i/o timeout
2024/04/28 01:50:12.395381 [error] dnsproxy: 10.0.0.1:53: response received over udp: "exchanging with 10.0.0.1:53 over udp: read udp 10.0.0.51:36158->10.0.0.1:53: i/o timeout"
2024/04/28 01:50:12.395409 [error] dnsproxy: upstream 10.0.0.1:53 failed to exchange ;aee03874-2f62-4298-9eb3-3a29536aa4bf.local.      IN       A in 20.000735423s: exchanging with 10.0.0.1:53 over udp: read udp 10.0.0.51:41347->10.0.0.1:53: i/o timeout
2024/04/28 01:50:12.395410 [error] dnsproxy: 10.0.0.1:53: response received over udp: "exchanging with 10.0.0.1:53 over udp: read udp 10.0.0.51:38392->10.0.0.1:53: i/o timeout"
2024/04/28 01:50:12.395416 [error] dnsproxy: upstream 10.0.0.1:53 failed to exchange ;aee03874-2f62-4298-9eb3-3a29536aa4bf.local.      IN       AAAA in 20.001288487s: exchanging with 10.0.0.1:53 over udp: read udp 10.0.0.51:36158->10.0.0.1:53: i/o timeout
2024/04/28 01:50:12.395423 [error] dnsproxy: upstream 10.0.0.1:53 failed to exchange ;aee03874-2f62-4298-9eb3-3a29536aa4bf.local.      IN       A in 20.000679419s: exchanging with 10.0.0.1:53 over udp: read udp 10.0.0.51:38392->10.0.0.1:53: i/o timeout

Additional information and/or screenshots

On 10.0.0.1 is a UDM Pro router

[felipejfc]

my bad. had a dns loop going on