DNS resolution does not work in Fedora 35, but works in Fedora 36

[antoineco]

Description

On the current HEAD version (8b3bcaf2627552cc4fe7828951d8318b810368fe)

DNS resolution is not functional on Fedora 35, but works on Fedora 36, although they both use systemd-resolved.

Lima configs

#f36

images:
  - location: http://ftp.halifax.rwth-aachen.de/fedora/linux/releases/36/Cloud/aarch64/images/Fedora-Cloud-Base-36-1.5.aarch64.qcow2
    arch: aarch64
    digest: sha256:5c0e7e99b0c542cb2155cd3b52bbf51a42a65917e52d37df457d1e9759b37512
  - location: http://ftp.halifax.rwth-aachen.de/fedora/linux/releases/36/Cloud/x86_64/images/Fedora-Cloud-Base-36-1.5. x86_64.qcow2
    arch: x86_64
    digest: ca9e514cc2f4a7a0188e7c68af60eb4e573d2e6850cc65b464697223f46b4605

#f35

images:
  - location: http://ftp.halifax.rwth-aachen.de/fedora/linux/releases/35/Cloud/aarch64/images/Fedora-Cloud-Base-35-1.2.aarch64.qcow2
    arch: aarch64
    digest: sha256:c71f2e6ce75b516d565e2c297ea9994c69b946cb3eaa0a4bbea400dbd6f59ae6
  - location: http://ftp.halifax.rwth-aachen.de/fedora/linux/releases/35/Cloud/x86_64/images/Fedora-Cloud-Base-35-1.2.x86_64.qcow2
    arch: x86_64
    digest: fe84502779b3477284a8d4c86731f642ca10dd3984d2b5eccdf82630a9ca2de6

Troubleshooting

The only obvious difference I can see is that Fedora 36 has a symlink from /etc/resolv.conf to the "stub" DNS config at /run/systemd/resolve/stub-resolv.conf, and its current DNS server set to the IPv6 fec0::3.

Whereas in Fedora 35, /etc/resolv.conf isn't symlinked and seems to be managed by NetworkManager. Symlinking manually to the same file as in Fedora 36 does NOT solve the issue.

DNS queries

f35:

$ resolvectl query fedoraproject.org
fedoraproject.org: resolve call failed: All attempts to contact name servers or networks failed

f36:

$ resolvectl query fedoraproject.org
fedoraproject.org: 38.145.60.20                -- link: eth0
                   140.211.169.196             -- link: eth0
                   152.19.134.198              -- link: eth0
                   8.43.85.67                  -- link: eth0
                   209.132.190.2               -- link: eth0
                   38.145.60.21                -- link: eth0
                   152.19.134.142              -- link: eth0
                   67.219.144.68               -- link: eth0
                   8.43.85.73                  -- link: eth0
                   2605:bc80:3010:600:dead:beef:cafe:fed9 -- link: eth0
                   2604:1580:fe00:0:dead:beef:cafe:fed1 -- link: eth0
                   2620:52:3:1:dead:beef:cafe:fed6 -- link: eth0
                   2600:2701:4000:5211:dead:beef:fe:fed3 -- link: eth0
                   2620:52:3:1:dead:beef:cafe:fed7 -- link: eth0

-- Information acquired via protocol DNS in 47.5ms.
-- Data is authenticated: no; Data was acquired via local or encrypted transport: no
-- Data from: network

Resolver status

f35:

$ ls -l /etc/resolv.conf 
-rw-r--r--. 1 root root 53 Nov  6 13:17 /etc/resolv.conf

$ resolvectl status
Global
         Protocols: LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported
  resolv.conf mode: foreign
Current DNS Server: 192.168.5.3
       DNS Servers: 192.168.5.3

Link 2 (eth0)
    Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 192.168.5.3
       DNS Servers: 192.168.5.3

f36:

$ ls -l /etc/resolv.conf 
lrwxrwxrwx. 1 root root 39 May  4  2022 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf

$ resolvectl status
Global
       Protocols: LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: stub

Link 2 (eth0)
    Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: fec0::3
       DNS Servers: 192.168.5.3 fec0::3

Additional notes

• This is not a network issue, I can reach both 192.168.5.3 and the public internet (by IP).
• Adding a public DNS server to /etc/systemd/resolved.conf, such as DNS=8.8.8.8, fixes DNS resolution.

[carlosjor]

Thanks, adding the public DNS servr solved my problem !