4.2 IP Address Types

IP addresses are usually categorized as static or dynamic.

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Private IP addresses were created by Internet Assigned Numbers Authority (IANA) and Internet Engineering Task Force (IETF) in 1996 to allow organizations to use specific IP addresses internally on their network. These IP addresses have been designated as private addresses and removed from the Global pool of available public Internet addresses.

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Your public IP address can be found by simply entering the command, "what is my IP Address," in a Google search engine. In most instances, when using this method to identify your IP address, it will be different from the IP address assigned to your computer. This is simply because Google's search engine is hosted on a server on the Internet. When that server looks to identify your computer, it sees your router's public IP address and not the private IP address assigned to your computer. This is a practical example of how NAT works.

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Network Address Translation (NAT)

NAT translates a private address to a public address

Static IP

addresses do not change and are consistent. If a network device is assigned a static IP address, that address will not change unless it is manually adjusted. Static IP addresses are often not used in home networks unless you are hosting your own server or website. However, static IP addresses are used much more frequently on corporate networks for troubleshooting and maintenance. In most instances, network devices such as switches, routers, servers, and printers are assigned a static IP address for remote access. These devices provide services to other devices on the network and should have a reliable connection. Static IP addresses are usually purchased in blocks from an Internet Service Provider (ISP) and can be expensive.

Dynamic IP addresses

change periodically and are usually provided to network clients by a DHCP server or router. Dynamic IP addresses are thought to be more secure and easy to distribute. If you have a dynamic IP address from your ISP, it can be changed without notification. These changes are usually unnoticeable and will not affect your day-to-day Internet activity. Dynamic IP addresses tend to be less expensive and are more common on most Ethernet LANs.

public IP address

is an address given to a device to communicate on the Internet. In order to transmit and receive data on the Internet, a device must have a unique public address. Public addresses can be assigned to various network devices, including routers, servers, and even personal computers.

private IP address

is given to a network device within a network and is not readily accessible or available on the Internet. In most instances, private IP addresses are protected by a firewall and used internally on the network; they do not directly connect to the Internet. For example, most devices on a LAN are issued private IP addresses. These private IP addresses allow internal communication among devices on the same network segment. Suppose data is transmitted from a computer with a private IP address that is destined for the Internet. In that case, the router that forwards the information performs Network Address Translation (NAT) .

The Internet Corporation for Assigned Names and Numbers (ICANN)

issues public addresses. ICANN is responsible for creating IP addresses and disseminating them to other organizations. In most cases, those organizations are ISPs who allocate public IP addresses to businesses, organizations, and end-users.

Three primary types of IP Addresses

unicast, broadcast, and multicast.