Where I work, we have many subdomains of our main domain pointing to ELB instances (with CNAME records) that are no longer in use (like my-loadbalancer-1234567890.us-west-2.elb.amazonaws.com). I realize this is a bad practice, but our developers seem to have done this a lot.
How dangerous is it that we have these DNS records? Can someone claim these instance names and start serving content on our subdomains?
As far as I know, every ELB instance's name contains 10 random digits that aren't controlled by the user. Is this correct? Can a user influence the generation of these digits in any way?