Suppose the following:

I have a database set up on database.mywebsite.com, which resolves to IP 111.111.1.1, running from a local DNS server on our network.

I have countless ASP, ASP.NET and WinForms applications that use a connection string utilising database.mywebsite.com as the server name, all running from the internal network.

Then the box running the database dies, and I switch over to a new box with an IP of 222.222.2.2.

So, I update the DNS for database.mywebsite.com to point to 222.222.2.2.

Will all the applications and computers running them have cached the old resolved IP address?

I'm assuming they will have.

Any suggestions along the lines of "don't have your IP change each time you switch box" are not too welcome as I cannot control this aspect of the situation, unfortunately. We are currently using the machine name of the box, which changes every time it dies and all apps etc. have to be updated with the new machine name. It hurts.