I have to move some file shares from a machine with Win2008R2 Enterprise to another with Win2008 R2 Standard. The goal is to have the file shares only on the second, dedicated machine.
Currently these shares are accessed by the users and some applications through UNCs similar to \\app.bizunit.example.com\share_name, where app.bizunit.example.com is an alias for the first machine.
The tricky requirement is to keep the same UNCs to avoid reconfiguring the related applications. But at the same time we would like to keep the app.bizunit.example.com alias pointing to the first machine so it could still be used to reach its remaining services.
I looked into DFS namespaces but unfortunately I didn't manage to accomplish the result I'm after.
What I managed to accomplish with DFS-N ("Stand-Alone Namespace" more specifically) though is to have the \\app.bizunit.example.com\<namespace_name>\share_name, which is not optimal.
You cannot have one name pointed at one server for UNC, and pointed to another server for other services. What you're asking is not possible.
The closest you'll be able to come is with a DFS namespace, which you can set up to ensure you don't have to update all your UNC links next time you change which server(s) host your shared files and folders.
As you noted, you won't be able to use the same path you use now, which is the server's hostname, but you will be able to have a namespace you can manage and transparently move hosts in and out of as you need.
Otherwise, as noted in MichelZ's answer, it is not possible to use DNS to direct different services to different hostnames. DNS is just not set up that way - it registers hostnames to IP addresses, and is unable to selectively translate the same hostname to different IPs.