Reverse lookups failing

gonsa · July 5, 2020, 3:06pm

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Expected Behaviour:

I don't know why so many requests and failing..
-Raspbian runing Pi-hole 5.0
-RaspberryPi 3b+

Actual Behaviour:

Lots of reverse lookups SERVERFAIL during the night..

Debug Token: Attachedpihole_debug.txt (55.4 KB)

Also my Pi-hole is working as DHCP and DNS. Why when does it shows this:
pi@raspberrypi:~ $ cat /etc/resolv.conf
Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 192.168.1.254
nameserver 2001:8a0:574c:e301:4d99:d1e0:7c76:4db3
search amor
pi@raspberrypi:~ $
The Pi-hole IP is 192.168.1.88

gonsa · July 5, 2020, 3:45pm

I edited /etc/dhcpcd.conf to make the static domain_name_servers=192.168.1.88 and after a reboot the /etc/resolv.conf stuck with the right nameserver=192.168.1.88 that is of the Pi-hole.

jfb · July 5, 2020, 4:47pm

SERVFAIL is frequently caused by incorrect date/time on the Pi.

gonsa · July 5, 2020, 8:04pm

I confirmed it with date command and time and date are correct..

jfb · July 5, 2020, 9:56pm

Next step - change your upstream resolver in Pi-Hole to something other than what you are using now.

gonsa · July 6, 2020, 12:00am

What do you mean? I'm using DNS over HTTPS, with Cloudflare, how do I change that now?

jfb · July 6, 2020, 12:11am

On the web admin GUI > settings > DNS, change it to something else. Cloudflared will continue to run but won't receive any queries from Pi-hole.

gonsa · July 8, 2020, 11:22am

Ok, I changed from the custom DNS 127.0.0.1#5053 (DNS over HTTPS) to a normal upstream DNS. The SERVERFAIL queries stopped...

What does this mean?

jfb · July 8, 2020, 12:36pm

This means that Cloudflared was not working properly.

gonsa · July 17, 2020, 9:22am

Selecting DNS 127.0.0.1#5053 (DNS over HTTPS) again brought back the SERVERFAIL queries.
It looks like is only on reverse lookbacks.
Should I ignore this?

jfb · July 17, 2020, 11:42am

Only if you don't want the PTR queries to be answered.

gonsa · July 17, 2020, 2:30pm

I wanted to understand why it is failing.

jfb · July 17, 2020, 2:50pm

Since this only happens with Cloudflared, you might find a solution on their forums. I don't know why this is happening.

system · August 7, 2020, 2:50pm

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