DNS not working from pihole

[gonzonia]

The issue I am facing:
Update fails due to inability to resolve hostnames

Details about my system:
I have 2 pi-holes set up for failover. They've been working great for years. I went to do a regular maintenance update and the secondary pi-hole (only active when the primary fails or isn't accessible) suddenly couldn't resolve domains so that it could update. After some testing I found that if I updated dhcpd.conf and changed

static domain_name_servers=127.0.0.1

to

static domain_name_servers=1.1.1.1

I was able to do an update. However, resetting back to 127.0.0.1 will revert to things not updating again.

Not sure what happened or why it won't work anymore

What I have changed since installing Pi-hole:
Very little other than creating the failover system (following this guide https://www.reddit.com/r/pihole/comments/d5056q/tutorial_v2_how_to_run_2_pihole_servers_in_ha/). I've primarily just run regular updates via apt update and apt upgrade.

[jfb]

Please upload a debug log and post just the token URL that is generated after the log is uploaded by running the following command from the Pi-hole host terminal:

pihole -d

or do it through the Web interface:

Tools > Generate Debug Log

[gonzonia]

Thank you.

https://tricorder.pi-hole.net/5fjl7p6z/

[jfb]

Nothing in your debug log indicates a problem. Pi-hole is receiving queries from network clients, processing them and returning results to the client.

*** [ DIAGNOSING ]: Pi-hole log
-rw-r----- 1 pihole pihole 59K Oct 10 19:00 /var/log/pihole/pihole.log
   -----head of pihole.log------
   Oct 10 00:00:08 dnsmasq[583]: query[AAAA] icretrieveapi.myicomfort.com from 192.168.99.26
   Oct 10 00:00:08 dnsmasq[583]: forwarded icretrieveapi.myicomfort.com to 8.8.8.8
   Oct 10 00:00:08 dnsmasq[583]: query[A] icretrieveapi.myicomfort.com from 192.168.99.26
   Oct 10 00:00:08 dnsmasq[583]: forwarded icretrieveapi.myicomfort.com to 8.8.8.8
   Oct 10 00:00:08 dnsmasq[583]: reply icretrieveapi.myicomfort.com is <CNAME>
   Oct 10 00:00:08 dnsmasq[583]: reply p2cuic3tmaretrieveapi.trafficmanager.net is <CNAME>
   Oct 10 00:00:08 dnsmasq[583]: reply p2cuic3appretrieveapi3.azurewebsites.net is <CNAME>
   Oct 10 00:00:08 dnsmasq[583]: reply waws-prod-dm1-299.sip.azurewebsites.windows.net is <CNAME>
   Oct 10 00:00:08 dnsmasq[583]: reply waws-prod-dm1-299-40a9.centralus.cloudapp.azure.com is 20.118.48.7
   Oct 10 00:00:09 dnsmasq[583]: reply icretrieveapi.myicomfort.com is <CNAME>
   Oct 10 00:00:09 dnsmasq[583]: reply p2cuic3tmaretrieveapi.trafficmanager.net is <CNAME>
   Oct 10 00:00:09 dnsmasq[583]: reply p2cuic3appretrieveapi1.azurewebsites.net is <CNAME>
   Oct 10 00:00:09 dnsmasq[583]: reply waws-prod-dm1-179.sip.azurewebsites.windows.net is <CNAME>
   Oct 10 00:00:09 dnsmasq[583]: reply waws-prod-dm1-179-pork.centralus.cloudapp.azure.com is NODATA-IPv6
   Oct 10 00:00:09 dnsmasq[583]: query[HTTPS] gdmf.apple.com from 192.168.99.56
   Oct 10 00:00:09 dnsmasq[583]: forwarded gdmf.apple.com to 8.8.8.8
   Oct 10 00:00:09 dnsmasq[583]: query[A] gdmf.apple.com from 192.168.99.56
   Oct 10 00:00:09 dnsmasq[583]: forwarded gdmf.apple.com to 8.8.8.8
   Oct 10 00:00:09 dnsmasq[583]: reply gdmf.apple.com is <CNAME>
   Oct 10 00:00:09 dnsmasq[583]: reply gdmf.v.aaplimg.com is NODATA

   -----tail of pihole.log------
   Oct 10 18:59:48 dnsmasq[583]: query[AAAA] lastovo.hr from fe80::7be1:a296:69e:5bb8
   Oct 10 18:59:48 dnsmasq[583]: gravity blocked lastovo.hr is ::
   Oct 10 19:00:00 dnsmasq[583]: query[PTR] 8.99.168.192.in-addr.arpa from 127.0.0.1
   Oct 10 19:00:00 dnsmasq[583]: config 8.99.168.192.in-addr.arpa is <PTR>
   Oct 10 19:00:00 dnsmasq[583]: query[PTR] 1.1.1.1.in-addr.arpa from 127.0.0.1
   Oct 10 19:00:00 dnsmasq[583]: forwarded 1.1.1.1.in-addr.arpa to 8.8.8.8
   Oct 10 19:00:00 dnsmasq[583]: forwarded 1.1.1.1.in-addr.arpa to 8.8.4.4
   Oct 10 19:00:00 dnsmasq[583]: forwarded 1.1.1.1.in-addr.arpa to 1.1.1.1
   Oct 10 19:00:00 dnsmasq[583]: forwarded 1.1.1.1.in-addr.arpa to 1.0.0.1
   Oct 10 19:00:00 dnsmasq[583]: reply 1.1.1.1 is one.one.one.one
   Oct 10 19:00:00 dnsmasq[583]: query[PTR] 1.0.0.1.in-addr.arpa from 127.0.0.1
   Oct 10 19:00:00 dnsmasq[583]: forwarded 1.0.0.1.in-addr.arpa to 8.8.4.4
   Oct 10 19:00:00 dnsmasq[583]: reply 1.0.0.1 is one.one.one.one
   Oct 10 19:00:00 dnsmasq[583]: query[PTR] 8.8.8.8.in-addr.arpa from 127.0.0.1
   Oct 10 19:00:00 dnsmasq[583]: cached 8.8.8.8 is dns.google

Can you provide some specific examples where Pi-hole is not resolving hosnmaes?

[gonzonia]

Hmmm....I'm going to set dhcpd.conf back to 127.0.0.1 and see if it stays working. Thanks.