A valid DNS name has to be (it does not have to have .com etc.)
1. A host name (label) can start or end with a letter or a number
2. A host name (label) MUST NOT start or end with a '-' (dash)
3. A host name (label) MUST NOT consist of all numeric values
4. A host name (label) can be up to 63 characters
I am new to perl. Can you write either one or 4 separate regular expression (i prefer multiple regex)?