We're in the process of migrating some sites over to AWS from another provider. Our current load balancer was available at a single IP so all the DNS entries were created with A records like:
A example.com 192.0.2.0
As you might know, AWS Elastic Load Balancer already provides an A Record for their Load Balancer so the sites are created with CNAME records like:
CNAME example.com production-lb1-<numbers>.us-west-1.elb.amazonaws.com
We set that record with a TTL of 900 Seconds we haven't seen it propagate out with
dig all example.com
Are there some magic DNS internals that stop name collisions like this? I.E. it doesn't want to create the CNAME because the A and CNAME would be pointing at contradictory information?
So does that mean I have to remove the A record and then add the CNAME? Are DNS controllers smart enough to not drop my site with nothing pointing at it? I.E. I would really not want the A name to go away when the CNAME isn't up yet. Thoughts?