ALIAS records are not widely standardized across DNS providers. Some (Route 53, DNSimple) have a native ALIAS record type. Others (Cloudflare) implement transparent CNAME flattening.
DNSControl adds an ALIAS record type, and leaves it up to the provider implementation to handle it.
A few notes:
A provider must “opt-in” to supporting ALIAS records. When registering a provider, you specify which capabilities you support. Here is an example of how the
cloudflare provider declares its support for aliases: