I am in the process of setting up a web app that will serve a lot of domains. My customers will register a domain and forward it to the web app server and then use the web app through that domain.
Until now I was planning to tell them to just change the A record to point to my server but then I figured that would probably become a problem if I wanna change servers or IP addresses... a lot of domains might have to be changed.
So I looked a bit into managed DNS but I think it actually does too much for what I want. As I understand it, my customers would change the name servers of their domains and I would do all the configuration through the managed DNS provider.
My concern is that my customers couldn't set up for example MX records on their domains anymore, they would have to go through me. What I really want is just an IP address which never changes and which my customers could set as the A record and which I could forward to my app server's IP address. If the latter changed, my customers wouldn't have to change anything, I could just update the "forwarding".
Is there anything like that?
As Shane Madden and joeqwerty pointed out, I could use CNAME records, i.e. tell my customers to point their domains to my domain. I actually thought about that before but what turns me off is that my customers would have to use "www.domain.com" since setting a CNAME for "domain.com" is not possible. I consider "www." a relict of the past and don't want to force anyone to use it.
Amazon EC2 seems to have something like that: http://aws.amazon.com/ec2/ (search for "Elastic IP Addresses") You get an IP address that you can dynamically assign to any EC2 instance. Isn't there something similar, an IP address that can dynamically be assigned to another IP address and just forwards all requests?