How and why are IP addresses hierarchically organized? 

IP addresses are organized and allocated hierarchically. This simplifies both IP address administration and the routing tables used by internet routers. The result is that IP addresses have a variable-length prefix that identifies the organization that administers them and path that is used when routing packets. The original internet design set up three address classes, although this decision has been revisited since then.
Credits: Talking: Geoffrey Challen (Assistant Professor, Computer Science and Engineering, University at Buffalo). Producing: Greg Bunyea (Undergraduate, Computer Science and Engineering, University at Buffalo).
Part of the www.internet-c... online internet course. A blue Systems Research Group (blue.cse.buffa...) production.