Re: systemd-resolved and single-label DNS entries

[Jeff Layton <jlayton@kernel.org>]

On Tue, 2025-08-26 at 14:53 +0200, Daniel Gomez wrote:
> On 26/08/2025 12.58, Jeff Layton wrote:
> > I'm hitting a problem with NFS testing on kdevops guests. Recently when
> > I bring up a guest, it's unable to resolve the name of the NFS server
> > via DNS.
> 
> FYI, nfstests works fine with Debian testing (forky). Both hosts and guests.
> 
> 


Thanks. Some questions:

1/ did your setup get the entries in /etc/hosts? That seems to be what
has changed recently. That's not working for some reason.

2/ Does forky use systemd-resolved? The problem is clearly there with
Fedora 42. The DNS server on the virtual bridge works fine:

----------------8<-----------------
$ dig @192.168.122.1 kdevops-nfsd.

; <<>> DiG 9.18.33 <<>> @192.168.122.1 kdevops-nfsd.
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24955
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;kdevops-nfsd.                  IN      A

;; ANSWER SECTION:
kdevops-nfsd.           0       IN      A       192.168.122.85

;; Query time: 0 msec
;; SERVER: 192.168.122.1#53(192.168.122.1) (UDP)
;; WHEN: Tue Aug 26 10:18:47 EDT 2025
;; MSG SIZE  rcvd: 57

$ resolvectl query kdevops-nfsd.
kdevops-nfsd.: 'kdevops-nfsd.' not found
----------------8<-----------------

It seems like we're doing something "unseemly" by putting bare names in
DNS like this, given that systemd-resolved won't pass them along.

Since systemd-resolved will only resolve bare names without a domain
using LLMNR, we should either take steps to make that work, or fix it
so that systemd-resolved will forward the requests (by setting up a
proper domain name and setting up the search path in the resolver).

-- 
Jeff Layton <jlayton@kernel.org>