I am contemplating using two different DNS hosts and am curious as to how a client system would cache the CNAME record. The reason I am going this route is that a primary domain that I would like to use is already hosted in one DNS service but the application is hosted in another service that has its own DNS handling that is integrated with the services.
Specifically what I am looking to understand is, if friendly.abc.com is a CNAME record that points to long-ugly-url.hosted-service.com which is itself hosted (DNS and application) on another service with an IP of 184.108.40.206, will the clients accessing friendly.abc.com be caching long-ugly-url.hosted-service.com or 220.127.116.11? The reason I ask is that if it is the former, then the long-ugly-url.hosted-service.com A record can have a short TTL and it can be changed quickly while the friendly.abc.com can be set at a higher TTL but still have changes "propagated" quickly. If it is the latter, then both would need to have short TTLs for responsible clients to see the changes quickly.