# Domain concepts and requirements | answer.cloud Docs

> Canonical source: [Domain concepts and requirements | answer.cloud Docs](https://www.answer.cloud/docs/domains/overview/)

Understand the default Answer Cloud address, paid custom domains, canonical hostnames, optional apex forwarding, HTTPS activation, and the separate companion setup path.

overview

# Domain concepts and requirements

Understand the default Answer Cloud address, paid custom domains, canonical hostnames, optional apex forwarding, HTTPS activation, and the separate companion setup path.

Reviewed November 1, 2026

A hosted site starts with an Answer Cloud address such as `example-site.answer.cloud`. A custom domain gives it a hostname you control, such as `www.example.com`, when the site's plan includes that feature.

Domain setup requires both Answer Cloud configuration and records at your DNS provider. Entering a hostname in the dashboard does not change DNS by itself.

## Hostnames and canonical addresses

| Term                 | Example               | Meaning                                               |
|----------------------|-----------------------|-------------------------------------------------------|
| Apex                 | `example.com`         | The registered domain without a subdomain             |
| Canonical hostname   | `www.example.com`      | The preferred public host serving the site            |
| Subdomain            | `help.example.com`    | A host that can be configured separately from the main website |
| Default site address | `example-site.answer.cloud` | The site's Answer Cloud address                        |

For hosted custom domains, entering an apex such as `example.com` selects `www.example.com` as the canonical host. Optional apex forwarding can redirect the bare domain to that canonical address. Entering a subdomain such as `help.example.com` keeps that hostname as canonical.

The MCP `include_apex` option defaults to false. Choose apex forwarding deliberately: routing the root domain to a help or AI subdomain is usually inappropriate if another website still uses the apex.

## DNS and HTTPS are separate checks

The domain configuration supplies routing records and certificate validation records. Ownership verification also requires the domain's specific TXT record, visible in the site's Domains dashboard. Copy the actual values for your site; do not reuse another site's validation token or an example IP address.

After DNS is correct, certificate issuance, attachment, HTTPS reachability, and public routing still need to complete. `check_domain` reports the latest checks, certificate status, error, and last-check timestamp. Use `refresh: true` to queue a fresh check after editing DNS.

Keep certificate validation records in place to support continued certificate management. Do not edit unrelated MX, mail, or third-party verification records while configuring a website hostname.

## Release workflow and companions

With [independent releases](https://www.answer.cloud/docs/hosting/environments/) active, the Answer Cloud address is used for staging and the active custom domain for production. Without that workflow, the default address follows the site's normal live behavior.

An existing website companion uses a separate organization-level AI-subdomain integration. The hosted `set_custom_domain` MCP tool rejects companion CMS sites. Follow [companion subdomain setup](https://www.answer.cloud/docs/domains/companion-subdomain/) and preserve the main website's DNS.

Use [Connect a custom domain](https://www.answer.cloud/docs/domains/connect/) for a hosted site or [DNS troubleshooting](https://www.answer.cloud/docs/domains/troubleshooting/) when a configured hostname is not activating.