MAC & IP addresses 

MAC address

A Media Access Control (MAC) address is a 48-bit address that is used for communication between two hosts in an Ethernet environment. It is a hardware address, which means that it is stored in the firmware of the network card.

A MAC address is supposed to be globaly unique. Each network card vendor gets its share of addresses (represented by the first 24 bits).

The address is written in the form of 12 hexadecimal digits. For example, consider the following MAC address:

D8-D3-85-EB-12-E3

Every hexadecimal character represents 4 bits, so the first six hexadecimal characters represent the vendor (in this case, Hewlett Packard).

How to find out your own MAC address?

If you are using Windows, enter the Command Prompt (Start – Programs – Accessories – Command Prompt). Type the ipconfig/all command and you should see a field called Physical address under the Ethernet adapter settings:

 If you are using Linux, type the ifconfig command. You should see your MAC address referred to as HWaddress.

IP address

An IP address is a 32-bit number that identifies a host on a network. It is usually written in the form of four decimal numbers seperated by periods (e.g. 10.0.50.1).    

In contrast to MAC address, an IP address is a logical address. Any device that wants to communicate with other device using TCP/IP needs to have an IP address. It can be configured manually or it can be obtained from a DHCP server.

The term “IP address” is usually used for IPv4, which is the fourth version of the IP protocol. A newer version exists, IPv6, and uses 128-bit addressing.

Private IP addresses

There are three ranges of addresses that can be used in a private network (e.g. your home LAN). These addresses are not routable through the Internet.

Private addresses ranges:

10.0.0.0 – 10.255.255.255
172.16.0.0 – 172.31.255.255
192.168.0.0 – 192.168.255.255

How to find out your IP address

Windows users:

Enter the Command Promt (Start – Programs – Accessories – Command Prompt). Enter ipconfig. You should see a field called IP address.

Linux users:

Enter ifconfig. You should see a field called inet addr: