lecture1:Lecture1: IP Address Classes

IP address space is divided into public and private spaces.

Private addresses are reserved IP addresses that are to be used only internally within a company’s network, not on the Internet.
public addresses designated for use in networks that are accessible on the Internet

The following figure illustrates the use of private and public addresses in a network.


RFC 1918, Address Allocation for Private Internets, defines the private IP addresses as follows:
10.0.0.0 to 10.255.255.255
172.16.0.0 to 172.31.255.255
192.168.0.0 to 192.168.255.255
The remaining addresses are public addresses.
*The network use private and public address
* A router or firewall act as the interface between the private and public IP address.
* Network Address Translation (NAT) or
*Port Address Translation (PAT)
*used to translate from private to public addresses and vice versa.
*NAT or PAT is required if accessibility to the public Internet or public visibility is required.
IPv4 addresses are categorized into five classes: A, B, C, D, and E.

Only Class A, B, and C addresses are used for addressing devices.

Class D is used for multicast groups.

Class E is reserved for experimental use.

This use of address space is referred to as classful addressing.