Azure SQL Managed Instance DNS Alias returns ResourceNotFound although resource type is advertised(West Europe)

Question

We are attempting to create a DNS Alias for an Azure SQL Managed Instance using the documented resource type: Microsoft.Sql/managedInstances/dnsAliases

The following has been validated:

• Managed Instance exists and is in Ready state.
• Microsoft.Sql resource provider is registered.
• Resource provider advertises: Microsoft.Sql/managedInstances/dnsAliases
• API versions exposed include: 2025-01-01 & 2025-02-01-preview & 2025-08-01-preview
• GET against the Managed Instance succeeds: GET /managedInstances/{MI}
• GET against the DNS Alias collection returns: GET /managedInstances/{MI}/dnsAliases
  { "error": { "code": "ResourceNotFound" } }
• PUT against: PUT /managedInstances/{MI}/dnsAliases/{Alias}
• results in an Activity Log entry for: Microsoft.Sql/managedInstances/dnsAliases/write

but ultimately fails with: HTTP 404 NotFound

The backend error references the regional SQL control-plane endpoint: management.<region>.control.database.windows.net

Additional observations:

• Resource Graph returns no existing Microsoft.Sql/managedInstances/dnsAliases resources.
• The issue occurs with multiple API versions.
• The parent Managed Instance resource is fully accessible.

Questions:

1. Is Azure SQL Managed Instance DNS Alias currently supported and operational?
2. Are there any undocumented prerequisites, feature registrations, or regional limitations?
3. If no aliases exist, should a GET against /managedInstances/{MI}/dnsAliases return an empty collection rather than ResourceNotFound?
4. Has anyone successfully created an Azure SQL Managed Instance DNS Alias recently using the documented REST APIs?

Any guidance would be appreciated.Additional observations:

• Resource Graph returns no existing Microsoft.Sql/managedInstances/dnsAliases resources.
• The issue occurs with multiple API versions.
• The parent Managed Instance resource is fully accessible.

Questions:

1. Is Azure SQL Managed Instance DNS Alias currently supported and operational?
2. Are there any undocumented prerequisites, feature registrations, or regional limitations?
3. If no aliases exist, should a GET against /managedInstances/{MI}/dnsAliases return an empty collection rather than ResourceNotFound?
4. Has anyone successfully created an Azure SQL Managed Instance DNS Alias recently using the documented REST APIs?

Any guidance would be appreciated.