How to debug DNS lookups?

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agroszer
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How to debug DNS lookups?

#1 Post by agroszer » 13 Jan 2023, 17:43

Something is wrong with my units, they somehow cannot lookup host by DNS.
A 'dig' or 'ping' like command would be nice, but don't find such in the docs.

TD-er
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Re: How to debug DNS lookups?

#2 Post by TD-er » 13 Jan 2023, 17:49

Which 'direction' of DNS issues to you mean?
Reaching the ESPEasy nodes via their mDNS .local name, or DNS lookup from the ESPEasy node to somewhere else?

Are those DNS lookups to local hosts, or is it to some external host (e.g. a host from the NTP pool)?
What kind of DNS lookups are these when they are local? Should these be resolved by the router or some local DNS server, or are these mDNS lookups (thus ending with .local in the name) ?

Also what build and what platform (ESP8266/ESP32) are you running?
Did it work before on an older build?

agroszer
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Re: How to debug DNS lookups?

#3 Post by agroszer » 14 Jan 2023, 08:11

I'm using Build: ESP_Easy_mega_20221224_climate_ESP8266_4M1M Dec 24 2022

Trying to set controller / Generic HTTP address by name, but somehow does not work. IP works fine.
Lookup is for a local host, tries from other local (linux) PCs work fine. DNS server is the local router, set by DHCP.
Haven't tried an earlier build, just started with one.

Tho as far as I remember I had problems with sending data to ThingSpeak when the host was specified by FQDN. There also IP works fine.

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Re: How to debug DNS lookups?

#4 Post by TD-er » 14 Jan 2023, 12:02

What timeout is set in the controller?
My first idea is to increase the timeout.

Also do you use a domain name ending in .local?
Or is it only to be resolved via your local DNS server?
So just to be sure, the IP set as DNS in your config (shown on the sysinfo page, also when using DHCP) is the IP of your router? (or at least the device running a DNS service) is reachable from the subnet assigned to the ESP node?
Typically "guest" subnets do not use the same DNS in their DHCP setup.

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