I have a case where after a seemingly random amount of time DNS lookups for internal hosts fail, and I don't understand why or what to do about it.
System is PopOS 22.04 LTS (basically Ubuntu), using NetworkMonitor where the Wired connection is configured like this
ipv4.dns: 192.168.218.215,192.168.218.1,8.8.8.8
ipv4.dns-search: lan,local,mydomain.com
.1 is the eero router, which I am married to because of Frontier Fios. .215 is an OpenWRT router which serves the IOT devices. Also, because eero doesn't correctly answer DNS queries about its own DHCP clients (argh!), I have added a number of entries to the OpenWRT DNS configuration for eero DHCP clients. Pretty much everything gets static infinite leases from DHCP so they keep the same IP address.
In the success case, I run "nslookup homeassistant", a DNS query is sent to .215 and answered. The same query is made by Apache2 when this system receives an HTTPS request which it needs to reverse proxy to HA (I already had this web server with an SSL cert, it seemed easiest to gatekeep HA that way).
In the failure case, Wireshark shows me that the only DNS request made is going to .1, and it fails. It does not send a packet to .215 at all even though it is configured first. It does not see the failure and then consult the other configured addresses. Further nslookups do exactly the same, talking only to .1, so I can't see it being some kind of round robin issue. What could be happening here?
nmcli con down Wired; nmcli con up Wired
restores it to the normal working state – mostly. nslookup works again, but sometimes incoming HTTPS requests appear to not even reach Apache, though I don't see how that's possible, and rebooting is what it takes to fix that.
Anyone got a handle on this situation?
Source: r/dns · by /u/lordbah