It's not a real record in the sense that it's never sent to the client so it doesn't really matter no ? It's just a convenient way to say "return an A record or that fqdn" on the configuration side.
Yeah, you should never see anything like "IN ALIAS" in the output of dig, for example, and getaddrinfo(3) wouldn't know what to do with that sort of record. It's all internal to the authoritative NS.
...which is a bummer, because doing this adds a weird sort of black box step in the DNS resolution chain between client and server. It makes troubleshooting DNS problems not so much fun.
