Keeping DNS at one place. What possibilities are out there?

I host a couple of websites for some customers. So basically what they do is change their A Record to my server's IP and everything works fine.

Now I want to upgrade my server and of course my clients have to change their A Record.

So what I want for the future is to keep my flexibility in choice of servers without having to annoy my customers with changing their A Record.

Basically what would be great is a nice service which is reliable and gives me the possibility to redirect the A Record to a new server. Also I thought of using a second server as a load balancer.

Anyone good experiences with either of these solutions or even has other ideas?

From stackoverflow

• What you're looking for is either a dynamic DNS service (there are many) or to just run your own DNS servers and have your clients make your servers authoritative for their domains.

  Stefan Koenig : Yes I've looked at them, but I'm not sure if they are suitable for my problem. I just want to manage the A record, the MX records are managed by my customers themselves. So are they still suitable? It seems that dyn DNS services demand a change of the NS for the domain. That's not what I want.

  chaos : You should be able to tell a dynamic DNS service to manage a subdomain like Dave Webb describes. If they demand to take over your entire domain, stay far away.

• Your customers could create a www subdomain instead of an www A record and the delegate this domain to your DNS server. You could then decide to which webserver this should send users' HTTP requests to with a default * A record.

  Stefan Koenig : I'm actually trying this solution with one domain, still waiting for propagation.

• We host our own DNS servers and instruct the client to point the domain at them. There really is no other good way to handle it. As far as load balancing, get a load balancer (dedicated hardware or a software appliance) and set it up to route info from the public IPs on the load balancer to the private IPs of the server. This gives you the flexibility to move servers around internally without ever changing the public IPs.

  Stefan Koenig : Yeah I probably will choose the load balancing solution, it gives me the highest flexibility. Any experience of the workload for a software load balancer and up to 50.000 visitors a month?

  Chris : We run Zeus ZXTM on a linux box with 4GB of ram and 2x dual core CPUs. Haven't had any issues on sites serving up to 1 million visitors a month.

• Create a www.myhostingservice.example in your zone and ask your clients to make www.clientdomain.example an alias (CNAME) pointing to www.myhostingservice.example.