IP Addresses

Everything that is connected to the internet (your computer, our website etc.,) has a unique IP address. This is necessary to communicate with other devices, users, and computers on the Internet. Your IP address is similar to a telephone number, each one being unique and used to identify a way to reach you and only you.

Private Addresses

Some IP addresses are set aside for internal private use for computers not directly connected to the Internet. These IP addresses are not supposed to be routed through the Internet, and most service providers will block the attempt to do so. These IP addresses are used for internal use by company or home networks that need to use TCP/IP but do not want to be directly visible on the Internet. These IP ranges are:

Typically, if your computer is connected through a router it will be assigned an IP in the range 192.168.xxx.xxx by your router and the router itself will communicate with the internet using the IP address assigned by your ISP.

169 IP Address

This is the result of a feature built into most Windows-based operating systems called automatic private IP addressing (APIPA).

APIPA enables a computer to automatically assign itself an IP address when there is no DHCP server available. When a DHCP client boots up, it first looks for a DHCP server to obtain an IP address and subnet mask. If the client is unable to find the information, it uses APIPA to automatically configure itself with an IP address from a specific range that has been reserved for Microsoft by the Internet Assigned Numbers Authority (IANA). That IP address range is 169.254.0.1 - 169.254.255.254. The idea behind this is that if a network's DHCP fails each machine will default to a 169 IP address and some form of connectivity will still be possible. However, this is of no use to a home computer connected directly to the internet.

The APIPA service will continuously check for the presence of a DHCP server (every five minutes, according to Microsoft). If it detects a DHCP server on the network, APIPA stops and the DHCP server replaces the APIPA networking addresses with a dynamically assigned address.

So Why has this happened to my Computer?

This is the 64,000 dollar question. It can be caused by malfunctions or corruption in certain parts of Windows (Registry, Winsocks etc.,), a badly configured/ damaged firewall or other security software, spyware and viral infections or even the removal of such parasites. In short, there are countless reasons for getting the dreaded '169' and it is probably more productive to focus on fixing the problem rather than worrying excessively about the cause.

Note: Occasionally, your ISP, modem or router could be at fault by not issuing an IP address to your computer. This is not often the case but should be taken into account.