What is a MAC Address?

Every device connected to the Internet from a home or office network, has its own unique MAC Address. The MAC address is used to identify a device so we can send it information, for instance a network-ready printer - or identify who has sent us information, for example from a remote PC. However, for addressing purposes we will also give each device connected to our network an IP Address which is the one that will be most familiar to many of you. This means that every addressable device on your network will have both a MAC Address and an IP Address.

A MAC address is a permanent feature of any device. Generated at the time of the device's manufacture, the address is unique and cannot be changed. A MAC address has 12-digits and will look something like this:

• 00-11-50-73-AD-1A 

The first part of the address (00-11-50) is known as the Vendor Code, and it will tell you who the manufacturer is. So in this example we know that the address is part of a series allocated to Belkin who produce routers. The second part of the address (73-AD-1A) is a set of random digits chosen by Belkin to ensure the MAC Address will be unique.

Security

Most routers will allow you to use a feature called MAC Address Filtering. If this feature is enabled, you'll then have to enter all the MAC addresses of the devices you wish to allow to use your network. Because every device in the World is given a unique MAC Address that is 'burned-in' - in other words you cannot change it - this makes it an almost fool-proof method of securing your network against unauthorised access.