Types of IP Addresses

Routers assign IP addresses to computers in their networks.

Internet Protocol (IP) addresses are numbers assigned to computers and other hardware in networks. IP addresses serve in identifying a computer or device and allow information to be routed to and from the machine or device in an organized way. There are a few different types of IP addresses, ranging from local to public addresses.

Local IP Addresses

When a computer is part of a local network, such as in a home or business, it is assigned a local IP address by the network's router. Every machine or host on the network must have an IP address to communicate with other devices locally. Most routers are set to automatically assign IP addresses to a computer when it first connects to their networks. This automated IP address system is called Dynamic Host Configuration Protocol (DHCP).

Public IP Addresses

Local IP addresses can not be used to identify a machine outside of its network due to the limited quantity of IP addresses. This means that a public IP address must be given to a network to allow for communication through the Internet. Usually, Internet Service Providers (ISPs) provide each network with one public IP address. This public IP address is assigned to the network's modem, and serves as identification for all computers on the network.

IPv4 and IP Classes

The current standard in IP addressing as of 2011 is IP Version 4 (IPv4.) IPv4 is in use by most networks and is organized by a class system. There are three classes of IPv4 addresses. Class A, class B and class C. Each class contains a range of IP addresses, beginning with the 0 to 127 range of class A. An example of a class A IP address would be 10.10.10.10. The four sets of numbers are designed to identify a machine or host, each set further pinpointing its identity. Class B and class C IP addresses fall into the 128 to 191 and 192 to 223 ranges, respectively. Given the limited network possibilities of the IP classing system, it is becoming less relevant with the introduction of IPv6.

IPv6

Given that there is a limited supply of IP addresses in the IPv4 system, a new system with more addresses is being implemented as of 2011. The new standard for IP addresses is IP version 6, or IPv6. IPv6 allows for more than a trillion IP addresses and eliminates networking problems associated with duplicate IP addresses. An example of an IPv6 would be 2000:8761:s765:7654:8987:5151:9090:7422 compared to an example IPv4 address of 192.168.22.24.

References

• Cornell University: IP Addresses, Subnetting and Sub-subnetting
• Cisco: IP Addressing and Subnetting for New Users
• Lincoln University: IP Address
• IT Knowledge Exchange: IPv6; How Many Is That In Numbers?

Resources

• Harvard Business School: When the Internet Runs Out of IP Addresses