[Discuss] Debian resolv.conf

[epp at mcom.com]

Happy New Year.

I have installed Debian 10 on my desktops, due to an issue with a prior 
Linux OS and noticed some differences after installation. Specifically 
with resolv.conf.

System 1's resolv.conf only contains:

Generated by Connection Manager
nameserver ::1
nameserver 127.0.0.1


System 2's contains:

domain (comcast)
search (comcast)
nameserver (comcast primary IPv4)
nameserver (comcast secondary IPv4)

(There is no reference to System 2's resolv.conf being generated by 
Connection Manager.)


When I tested the browser (Firefox) on System 1 at Comcast's IPv6 test 
mirror:
https://test-ipv6-vm3.comcast.net, it went through the tests and 
although it reported 10/10, there was an indication that the browser has 
a real working IPv6 address, but is avoiding using it.

When Firefox was tested on System 2 at the same site, it also reported 
10/10, but did not indicate it was avoiding IPv6.

Although I used the same image to install Debian on both, I used the 
graphical installer on System 1, which during the process, did not 
prompt for the domain name, nor did it ask for a root password, unlike 
the regular (text-based) installer. I have since created the root password.

Are these unexpected differences with System 1, cause for concern? 
Should I reinstall Debian on it, using the text-based installer instead?

Thanks in advance.