> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nerdit.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Manage domains

> Bind a domain to an app and interpret the App's DNS and reachability checks.

A domain configured here points directly at your machine. It is separate from Nerdit's hosted app address and requires suitable DNS, incoming connectivity, and Engine networking configuration.

Read the [Engine networking and HTTPS guide](/engine/networking) first. The App cannot configure your router, DNS provider, or certificate authority settings for you.

<Steps>
  <Step title="Open the app's domains">
    In **Machines**, select the online machine. Open the manageable app's **… → Domains** panel.
  </Step>

  <Step title="Add the name">
    Enter a domain you control, such as `app.example.com`, and choose **Add domain**. Wait for the machine to confirm the binding.
  </Step>

  <Step title="Follow the DNS guidance">
    Review the observed address and any suggested A or AAAA record. Make the change at your DNS provider. Use **Check again** after DNS changes have propagated.
  </Step>

  <Step title="Complete HTTPS on the machine">
    Review the certificate message. Public certificate requests require local Engine administration; the App does not request ACME certificates. Follow the linked [HTTPS prerequisites and instructions](/engine/networking).
  </Step>

  <Step title="Test the application">
    Open the domain from a separate internet connection and check the application's actual response and certificate. A DNS match alone does not prove that the app works.
  </Step>
</Steps>

## Interpret a check

| Observation                                | Next action                                                                                                                       |
| ------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------- |
| Points at this machine                     | Check HTTPS and the app itself. The result is a dated observation, not an availability guarantee.                                 |
| Points elsewhere                           | Compare the displayed address with your DNS records and intended machine.                                                         |
| Not resolving yet                          | Check the record name and wait for DNS propagation before checking again.                                                         |
| Cannot reach the machine from the internet | Check incoming connectivity, router forwarding, firewall rules, and provider restrictions. DNS changes alone cannot bypass CGNAT. |
| The check could not run                    | Retry later. A failed check does not remove the domain binding.                                                                   |

**Offline** means the App cannot manage the machine at that moment. A directly served domain may still be serving requests.

## Release a domain

Choose **Release…** next to the name and confirm **Release**. The machine stops serving that binding. Review and remove or update the corresponding DNS record separately; the App does not delete it at your provider.