(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}|(?:\w+\.)+\w{2,3})
[download]

Solves the above hostname issue but misses a good few invalid values.

(\d+|(?:\d{1,3}\.){3}\d{1,3}|(?:\w+\.)+\w{2,3})
[download]

Is better but you are far better using Regex::Common functions.

Hope it helps
UnderMine