IP Classes
The Internet Assigned Numbers Authority (IANA) devised the hierarchical IP addressing structure.
The Internet Network Information Center (InterNIC) assigns these addresses to public, private, and government organizations.
Five different groups of IP addresses, labeled Class A through E, exist on the Internet.
The first three classes, Classes A, B, and C, are assigned to governments, companies, schools, and public entities for use on the Internet.
The other two classes (D and E) are reserved for multicasting and experimentation.