DNS-based strategies for showing a nice “Currently

Question

How can I make that a site automagically show a nice "Currently Offline" page when the server is down (I mean, the full server is down and the request can't reach IIS)

Changing the DNS manually is not an option.

Edit: I'm looking to some kind of DNS trick to redirect to other server in case the main server is down. I can make permanent changes to the DNS, but not manually as the server goes down.

Answer 1

I believe that if the server is down, there is nothing you can do. The request will send up a 404 network error because when the web address is resolved to an IP, the IP that is being requested does not exist (because the server is down). If you can't change the DNS entry, then the client browser will continue to hit xxx.xxx.xxx.xxx and will never get a response.

If the server is up, but the website is down, you have options.

EDIT

Your edit mentions that you can make a permanent change the IP. But you would still need a two server setup in order to achieve what you are talking about. You can direct the DNS to a load balancer which would be able to direct the request to a server that is currently active. However, this still requires 100% uptime for the server that the DNS points to.

No matter what, if the server that the DNS is pointing to (which you must control, in order to redirect the traffic) is down, then all requests will receive a 404 network error.

EDIT Thanks to brian for pointing out my 404 error error.

Answer 2

Some server needs to dish out the "currently offline page", so if your server is completely down, there will have to be some other server serving the file(s), so either you can set up a cluster of servers (even if just 2) and while the first one is down, the 2nd is configured only to return the "currently offline page". Once the 1st server is back up, you can take down the 2nd safetly (as server 1 will take all the load).