On Thu, Feb 09, 2023 at 05:17:42PM -0500, gene heskett wrote: > Maybe I am the last on the planet still using hosts files, but I doubt that
You are not. Some of my systems at work use them. Technically, they *all* do if you count the mandatory entries for the NIS servers. > I also think it would be foolhardy to publish all that on a public list. All you need to do is find ONE computer which can't ping one OTHER computer, due to name lookup failure. This gives us two hostnames. The one you're typing the commands on, and the one you're trying to ping. Let's call them "source" and "dest". We don't care ANYTHING about how dest is configured. It's totally irrelevant. "dest" doesn't even have to exist. It could be entirely imaginary. All that matters is "source" THINKS it exists. What we care about is how "source" is configured. So, we'll want the version of Debian that it's running, and then the following: 1) A paste of you running "ping dest" and the resulting output. 2) A paste of you running "getent hosts dest" and the resulting output. 3) A paste of "grep hosts: /etc/nsswitch.conf". 4) A paste of "grep -i dest /etc/hosts". 5) A paste of "cat /etc/host.conf". 6) A paste of "cat /etc/resolv.conf". Just now, on my own system, I did an "strace getent hosts gene" to see what files it looks at. The results were surprising. The first file it looks at (besides libraries and locale stuff) is /etc/host.conf. The second file it looks at is /etc/resolv.conf. The third is /etc/nsswitch.conf. The fourth is /etc/hosts. (It actually opens this one twice, and I have no idea why.) This tells me that my knowledge of Linux name resolution is incomplete. Clearly there're some things I still need to learn, and I'm happy to do that. If you'd like us to help you solve your name resolution problem while we're learning, we're going to need all of the relevant details.
