DNS and domain troubleshooting

# Common issues

Domain routing fails for a predictable set of reasons. Review each scenario to identify your problem.

# Wrong DNS settings

Compare your actual DNS records against the desired settings shown in the dashboard. Mismatches here are the most common cause of routing failure. Check for conflicting or outdated records that might override the correct ones. See setting up external domains for the correct record values.

# Time delays

Many domain providers default to a long TTL (Time To Live). The TTL value is in seconds. Often it's 3600 meaning one hour. The TTL caching itself is actually a good thing as it helps to reduce round trips. Most domain providers let you set down the TTL, which is very useful to do before moving domains. See below on how to query the current DNS settings.

# Internal routing issues

A 404 error appearing after DNS is correctly routed and traffic reaches fortrabbit usually signals a misconfigured app. Check your root path setting and any domain-specific URL settings in your app code. See also 404 troubleshooting.

# No DNS settings

Errors like DNS_PROBE_FINISHED_NXDOMAIN, This site can't be reached, or This webpage is not available indicate that DNS resolution has failed. The domain is either unregistered or has no DNS records. Contact your domain provider to register the domain and add DNS records.

# Certificate errors

Once a domain is correctly routed, the TLS certificate needs to be installed. This takes some additional time in which requests to the https version of the website will display a certificate warning in the browser. This is actually not a DNS issue, see the HTTPS troubleshooting guide.

# No domain configured with fortrabbit

Registering an external domain at your registrar is separate from configuring it in the fortrabbit dashboard. Both steps are required. Verify that the domain appears in your app's dashboard configuration.

# Debugging DNS issues

DNS problems are easiest to diagnose by inspecting live DNS records and comparing them against the expected configuration. Use these tools to verify propagation and identify mismatches.

# Use the dashboard as a guidance

When visiting your external domain within the dashboard, you'll see the desired and the currently active DNS values for the domain. Those two settings should match.

# Use dig to verify current DNS values

You can verify DNS settings with the dig command.

# Use a DNS checker website

You can also use DNS test websites to rule out caching, those can query your DNS entries from different locations at once.