Hmm, what you're suggesting smells of symbolic references, which should be avoided. Why not use a hash of hashes? The "top-level" keys would be the MAC address, and the value would be an anonymous hash with the IP for the key and the hostname for the value, like such:

%hash = (
         0810100292 => {
                        "192.168.1.1" => "mybox.myhome.com"
                        },
         0810100293 => {
                        "192.168.1.1" => "foo.myhome.com"
                        },
}
[download]

There's your "unknown number of hashes" all in one data structure. HTH.

Update Bah! I take too damn long to test the code that I post...

--

There are 10 kinds of people -- those that understand binary, and those that don't.