It's using a local dnsmasq server for caching, akin to what windoze does, only it uses an external service and not hidden behind the scenes.  You can remove dnsmasq, usually at least, and resolve direct against your dns servers, I usually start by removing the package, as I've had enough issues with it being weird, I tend to not like using it.

I'm presuming 192.168.1.4 and 192.168.1.1 are valid dns servers?

I'm having a weird issue that network manager has a bad dns stuck in it somewhere that keeps causing me site delays when it'll randomly put it back into my dns servers list as first.  It's not a setting I can find, or anything in /etc/, I'm thinking something in gconf settings lost, but might be something similar there if that 192.168.1.4 servers isn't valid.

This might be useful to see what servers dnsmasq is using.

https://askubuntu.com/questions/556852/how-can-i-tell-which-dns-servers-dnsmasq-is-using

-mb


On Fri, Dec 7, 2018 at 7:44 PM Jim <jim.nantz15@comcast.net> wrote:
Today I noticed a problem when I use Thunderbird to check my email on my
Kubuntu 18.04 box.  I got  the following error in Thunderbird: Failed to
connect to imap.comcast.net  However it will connect to
imap.comcast.net.  I also couldn't ping imap.comcast.net.

delboy@ladmo:~$ ping imap.comcast.net
ping: imap.comcast.net: Name or service not known
delboy@ladmo:~$

In Network manager I have  the following DNS servers in this order: 
192.168.1.4 192.168.1.1, 8.8.8.8 8.8.4.4.  I found this in /etc/resolv.conf

# Generated by NetworkManager
nameserver 127.0.0.53

If I change 127.0.0.53 to one of the DNS servers I have in Network
Manager, Thunderbird works again, but I'm not able to ping
imap.comcast.net. I get the same error I mentioned earlier.  I really
don't care if I can ping it or not as long as Thunderbird can connect to
it.   However when I reboot or restart Network Manager, resolv.conf goes
back to 127.0.0.3.

Is there some bug with Network Manager or has comcast manged to screw up
something?

thanks

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