In general, implementing ALIAS records through recursive resolution is a bad idea. Geo routing and other resolver IP-based policies will probably break, since

In general, implementing ALIAS records through recursive resolution is a bad idea. Geo routing and other resolver IP-based policies will probably break, since the authoritative name server has no way of knowing the resolver IP. Edns-client-subnet does not suffice in this case, since the authoritative name server may still base part of its decision on the resolver IP. A much bigger problem is that the forwarding name server can be used for DDoS amplification attacks and that its own resources can easily be exhausted by an attacker if the authoritative name server is slow to respond. If the forwarding name server opens a new socket for every query it makes, the set of available port numbers can easily be exhausted. If the forwarding name server reuses port numbers, then spoofing attacks become straight-forward. This does not mean ALIAS records are a bad idea in general. The Amazon Route 53 implementation resolves aliases internally. It is therefore limited it to AWS services, but you could, for example, point an ALIAS to CloudFront and point CloudFront to your website. CloudFlare offers a similar service.