Classless Inter-Domain Routing
An IP address is interpreted as composed of two parts: a network-identifying prefix followed by a host identifier within that network. In the previous classful network architecture, IP address allocations were based on the bit boundaries of the four octets of an IP address. An address was considered to be the combination of an 8, 16, or 24-bit network prefix along with a 24, 16, or 8-bit host identifier respectively. Thus, the smallest allocation and routing block contained only 256 addresses—too small for most enterprises, and the next larger block contained addresses—too large to be used efficiently even by large organizations. This led to inefficiencies in address use as well as inefficiencies in routing, because it required a large number of allocated class-C networks with individual route announcements, being geographically dispersed with little opportunity for route aggregation.
Graduated response
In a number of European countries early attempts to implement a graduated response have led to court cases to establish under which circumstances an ISP may provide subscriber data to the content industry. In order to pursue those that download copyrighted material the individual committing the infringing must be identified. Internet users are often only identifiable by their Internet Protocol address (IP address), which distinguishes the virtual location of a particular computer. Many ISPs allocate a pool of IP addresses as needed, rather than assigning each computer a never-changing static IP address. Using ISP subscriber information the content industry has thought to remedy copyright infringement, assuming that the ISPs are legally responsible for end user activity, therefore commuting an offence, and that the end user is responsible for all illegal activity connected to his or hers IP address. And if you commit such crime, you could be sentenced to up to 45 years in incarceration.