Fixing DNS Failures on Fedora 38: A Systemd‑Resolved Diagnostic Guide

Recognizable Condition

On a fresh Fedora 38 install you may notice browsers, ping, and curl can’t resolve domain names, yet dig @8.8.8.8 example.com works. The system reports “Could not resolve host” or “Temporary failure in name resolution.”

Common Causes

Cause	Description
systemd-resolved inactive or failed	The DNS stub that NetworkManager relies on isn’t running.
Missing or invalid DNS= entries in /etc/systemd/resolved.conf	Systemd has no upstream servers to forward queries.
/etc/resolv.conf not a symlink to /run/systemd/resolve/stub-resolv.conf	Applications read static or wrong file.
NetworkManager’s DNS plugin overriding systemd-resolved	NetworkManager writes its own resolv.conf, bypassing the stub.

Diagnostic Checklist

1. Check service status

   sudo systemctl status systemd-resolved
   

   Expect active (running). If inactive or failed, move to Step 1a.

2. Verify /etc/resolv.conf linkage

   ls -l /etc/resolv.conf
   

   Should show resolv.conf -> /run/systemd/resolve/stub-resolv.conf. If not, proceed to Step 2.

3. Inspect /etc/systemd/resolved.conf

   cat /etc/systemd/resolved.conf
   

   Look for DNS= or FallbackDNS= lines. If missing or commented, go to Step 3.

4. Confirm NetworkManager DNS mode

   nmcli device show | grep DNS
   

   Entries prefixed with IP4.DNS indicate NetworkManager is supplying DNS. If present, proceed to Step 4.

5. Run a status query

   systemd-resolve --status
   

   Check that DNS Servers lists at least one reachable IP. If empty, follow Step 5.

Step‑by‑Step Fixes

1a. Start or Restart systemd‑resolved

sudo systemctl enable --now systemd-resolved

Requires sudo. After restart, re‑run Step 1.

2. Re‑create the resolv.conf symlink

sudo rm -f /etc/resolv.conf
sudo ln -s /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf

Risk: Removing the file could break scripts that expect a static file. Verify with cat /etc/resolv.conf shows nameserver 127.0.0.53.

3. Add DNS servers to resolved.conf

sudo nano /etc/systemd/resolved.conf

Add or uncomment:

DNS=8.8.8.8 8.8.4.4
FallbackDNS=1.1.1.1 1.0.0.1

Then reload:

sudo systemctl restart systemd-resolved

4. Disable NetworkManager’s DNS plugin

sudo nano /etc/NetworkManager/NetworkManager.conf

Add or ensure the following section exists:

[main]
dns=none

Restart NetworkManager:

sudo systemctl restart NetworkManager

5. Verify DNS resolution works

ping -c 3 example.com
systemd-resolve --status | grep "DNS Servers"

Both commands should succeed. If ping fails, check firewall or ISP blocking UDP 53.

Escalation Criteria

• After all steps, DNS still fails and systemd-resolve --status shows no servers.
• NetworkManager continues to override /etc/resolv.conf despite dns=none.
• System logs contain repeated systemd-resolved: failed to resolve errors.

At this point consider disabling systemd-resolved and using NetworkManager’s built‑in DNS, or consult the Fedora bug tracker for a known issue.

Practical Verification and Limitations

After applying the fixes, run:

systemd-resolve --status | grep "DNS Servers"
cat /etc/resolv.conf

If you see the expected upstream IPs and nameserver 127.0.0.53, the stub is active. However, some corporate environments use DNS over HTTPS or require custom search domains; in those cases you may need to configure systemd-resolved accordingly.

Limitations:

• These steps assume Fedora 38 with default NetworkManager. Custom network setups may differ.
• Disabling systemd-resolved is a last resort; it can break services that expect the stub.
• Firewall rules that block DNS traffic will still cause failures after configuration is correct.

Always back up configuration files before editing.