Choose the correct hostname and project
Before attaching a domain, confirm whether you want the root name, a `www` variant, or a service subdomain to reach the project. These names can be configured independently. Select the project that contains the intended site or application and verify that the hostname belongs to the domain you control.
If the domain is not active in the account or its DNS is managed elsewhere, resolve that ownership and management state first. Do not attach a hostname to a test project simply to make its DNS appear configured; the project association determines which deployment will receive traffic for that name.
Verify routing after attachment
After the attachment completes, check the hostname in the hosting project's domain list and inspect the related DNS configuration. Test the exact address in a browser, including any alternate hostname visitors use. A root domain and `www` can produce different results if only one was attached or its DNS record is missing.
Keep attachment and redirect decisions separate. If one hostname should be canonical, configure and test a redirect intentionally rather than expecting the attachment alone to send visitors to another name. When detaching later, review the hosting association and DNS record together so you know whether the name will continue resolving elsewhere.