Need help with a forumla for mapping IP addresses to Private or Public defined spaces

Hello,

I need help with a formula. First to explain what I am doing. I have a macro that pulls specific data from a CSV, then I copy that extract to my master excel doc (setup by year), so I can put the data into pivot tables and charts. This is used to create "management" style reports.

This data has IP addresses in it. Both internal and external. Trying to find a formula that will look at Cell A, where the IP address is and input either External or Internal into column AA, based on the number.

Internal would be numbers between 10.0.0.0 and 10.255.255.255, 172.16.0.0 and 172.31.255.255, and 192.168.0.0 and 192.168.255.255. Anything not in those three ranges would show as External.

Thanks in advance.