Problem: An Internet Service Provider (ISP) must, as part of its service to customers, provide a Domain Name Server (DNS).

A DNS is a server that maintains a database of domain names, such as www.griffith.edu.au, and their corresponding Internet Protocol Addresses (IPA), such as 132.234.243.22. A domain name has only one IPA, but an IPA may have many domain names.

Define a class that simulates a DNS. It must have:

• a method for updating the DNS with a new domain name and its IPA;

• a method for returning the IPA for a domain name, or None if it does not exist; and

• whatever private attributes are required to support the methods.

Write a test program that allows the user to test the class, by typing in fake domain names and IPAs to update the DNS, and domain names to look up.