Release-upgrade 20.04. to 22.04.3 questions

[Bo Berglund]

On Wed, 18 Oct 2023 18:34:44 -0400, Bo Berglund <bo.berglund at gmail.com> wrote:

>It turns out that there are other problems as well...
>
>I have a script that should run from cron at boot in order to report the fact
>that the system has been restarted and to send the current network address.
>It is also set to do that every night at a specified time.
>
>*** This has stopped working starting from the upgrade. :-( ***
>
>When I try to run it manually it reports a strange error from the curl command
>used in the script (I have obfuscated the domain name for privacy):
>
>$ ./ipreport.sh 2
>Extracted Ethernet IP address: 10.0.0.236 00:50:56:9e:c6:86
>Extracted hostname: agivpnserver
>curl: (6) Could not resolve host: www.xxxx.com
>
>Where the address www.xxxx.com is my own domain where I host the reporting
>script...
>
>So then I tried on the command line:
>
>ping www.xxxx.com
>ping: www.xxxx.com: Temporary failure in name resolution
>
>If I do the same on another Linux box on the same LAN it does resolve the name
>and starts the pinging:
>
>$ ping www.xxxx.com
>PING www.xxxxd.com (93.188.2.53) 56(84) bytes of data.
>64 bytes from webfront3.webcluster.loopia.se (93.xxx.2.53): icmp_seq=1 ttl=48
>time=139 ms
>64 bytes from webfront3.webcluster.loopia.se (93.xxx.2.53): icmp_seq=2 ttl=48
>time=129 ms
>
>So something has happened to the networking system too on this release upgrade
>that makes it no longer able to resolve domain names...
>
>I also tried a university url in Sweden like so:
>$ ping www.sunet.se
>ping: www.sunet.se: Temporary failure in name resolution
>
>But on the other Linux box:
>$ ping www.sunet.se
>PING www.sunet.se (37.156.192.51) 56(84) bytes of data.
>64 bytes from sunet.se (37.156.192.51): icmp_seq=1 ttl=46 time=148 ms
>
>Where do I go from here to resolve the more important networking failure?

From:
https://tecadmin.net/resolved-temporary-failure-in-name-resolution-error-in-linux/


I added a new line to the file /etc/resolv.conf :

nameserver 8.8.8.8

After saving it my report script started working and I could poing domain names
as before.

Why did this happen on the do-reease-upgrade?
And what other surprises are waiting for me?


-- 
Bo Berglund
Developer in Sweden