Can the same custom domain be configured on two FusionAuth Cloud deployments simultaneously?

[FASupportBot]

I need to migrate a custom domain from one FusionAuth Cloud deployment to another. Currently, the custom domain is configured on a production deployment, and I want to transition it to a development deployment.

My intended migration approach is:

1. Configure and validate the custom domain and certificate on the dev deployment
2. Update DNS to point the domain to the dev deployment
3. Test and validate everything works correctly
4. Remove the custom domain from the production deployment

My questions:

• Can I configure the same custom domain on both FusionAuth Cloud deployments simultaneously?
• Are there any conflicts with certificate validation or provisioning when the same domain is on two deployments at once?
• Is this migration approach supported, or is there a recommended sequence to avoid certificate validation issues?

[FASupportBot]

No, you cannot configure the same custom domain on two different FusionAuth Cloud deployments at the same time.

The recommended migration sequence is:

1. Remove the custom domain from the production deployment
2. Configure the custom domain on the dev deployment
3. Configure a CNAME record pointing your custom domain directly to the dev deployment's durable hostname
4. Validate the certificate for the domain on the dev deployment

Important Considerations

DNS Propagation Time

• DNS changes take time to propagate
• Expect up to 30 minutes for DNS servers to recognize the changes
• Propagation may take longer depending on your DNS TTL settings
• Plan for this downtime window during your migration

Certificate Validation

• Certificate validation uses DNS-based methods
• You must complete the DNS configuration before certificate validation can succeed

To minimize downtime, prepare all configurations on the dev deployment beforehand, then execute the domain removal, DNS update, and certificate validation in quick succession.