New installation - DNS client not working on lan [solved]

vespaman · Last edited by vespaman on Tue Aug 20, 2024 3:10 pm; edited 1 time in total

So I have this strange (to me, anyway!) issue with a new laptop; the name resolution does not work for local network.

I have an old-ish dnsmasq server, which supplies addresses for local names, and it works fine with existing computers and mobile phones and so on.

But this new laptop will not ping, or browse to local network using name resolution. However, WAN names works just fine.
My /etc/resolv.conf has the correct setting showing my dnsmasq machine, and it is identical to another gentoo machine I have.

Could it be related to ipv6 somehow? I don't think most of my local (lan) stuff has ipv6 knowledge..
I learned by searching that there's a gai.conf in /etc/ that might be related, but this too looks identical to the working machines gai.conf.

Or more likely, did I miss to do something during installation? I used systemd on this machine, which I am not super confident with.

Edit: I should mention that I have tried both ethernet and wifi - same issue.

Edit2: So, now I realize that I do get name resolution on devices that are allocated dynamically from dnsmasq (i.e. devices in /var/lib/misc/dnsmasq.leases), but not from devices that exists in the hosts file on the dnsmasq server.

And this is working on all other computers and devices..

Hu · Administrator Joined: 06 Mar 2007 Posts: 22612

On both a working and non-working system, what is the output of dig local-dynamic-name @dnsmasq.server; dig local-nondynamic-name @dnsmasq.server? I want to understand whether dnsmasq is serving nondynamic names to anyone. If it is, then the problem is that the non-working system is not asking dnsmasq about those names. If it is not, then the problem is that the working system is somehow resolving those names without relying on an answer from dnsmasq.

vespaman · Posted: Mon Aug 19, 2024 12:11 pm Post subject:

Thanks for taking interest!

So think2 is one of the working laptops, think3 is the new, non-working.

Hu · Administrator Joined: 06 Mar 2007 Posts: 22612

I read that output to mean that dnsmasq provides the same, and presumably correct, answer to anyone who asks. Since I had you use the @server notation, think3 asked dnsmasq even if it otherwise would not. Therefore, I think the problem is that think3 is not asking dnsmasq for resolution when you use think3 normally. What if you run dig vaka without @server on each machine? I expect to see that think2 still asks dnsmasq, and that think3 asks something else - possibly a local systemd resolver. Also, what is the output of cat -n /etc/resolv.conf ; cat -n /etc/nsswitch.conf on think2 and on think3?

vespaman · Posted: Mon Aug 19, 2024 1:17 pm Post subject:

I see what you mean. However, think3 does not know the answer, so how would it know to choose a different path for its question?

And to confirm;

Hu · Administrator Joined: 06 Mar 2007 Posts: 22612

vespaman · Posted: Mon Aug 19, 2024 5:12 pm Post subject:

Spot on! Looks as if it is the [!UNAVAIL=return] that is causing the trouble. Not sure what's going on here. I'll rebuild world, over night, just to be sure.

Thanks

vespaman · Posted: Tue Aug 20, 2024 3:10 pm Post subject:

So rebuilding everything did not make any difference. I was hoping it would, since I had changed some CFLAGS (started with -znver3 and now -znver4) during installation of the machine.
In further inspection, 'mymachines resolve files myhostname dns' does work, but it takes a long time before the first ping result appears on screen.

The problem seems to be that I had systemd-resolved running on new machine, while not on other machine. So I simply stopped and disabled it, and now new laptop behaves better.