MAC Addresses & IP Addresses (Cambridge (CIE) O Level Computer Science)

• Devices on a network send and receive data, a device needs an address to ensure it sends data to the correct place

• There are two types of network address systems:

  • MAC Address 

  • IP Address

MAC Addresses

What is a MAC address?

• A MAC (Media Access Control) address is a unique identifier given to devices which communicate over a local area network (LAN)

• A network interface card is given a MAC address at the point of manufacture

• MAC addresses are static, meaning they can never change

• MAC addresses make it possible for switches to efficiently forward data to the intended recipient

• Any device that contains a Network Interface Card (NIC) has a MAC address assigned during manufacturing

• A device connecting to a local network already has a MAC address, if it moves to a different network then the MAC address will stay the same

• A MAC address is represented as 12 hexadecimal digits (48 bits), usually grouped in pairs

• The first three pairs are the manufacturer ID number (OUI) and the last three pairs are the serial number of the network interface card (NIC)

• There are enough unique MAC addresses for roughly 281 trillion devices

IP Addresses

What is an IP address?

• An IP (Internet Protocol) address is a unique identifier given to devices which communicate over the Internet (WAN)

• IP addresses can be static, meaning they stay the same or dynamic, meaning they can change

• IP addresses make it possible to deliver data to the right device

• A device connecting to a network will be given an IP address, if it moves to a different network then the IP address will change

IPv4

• Internet Protocol version 4 is represented as 4 blocks of denary numbers between 0 and 255, separated by full stops

• Each block is one byte (8 bits), each address is 4 bytes (32 bits)

• IPv4 provides over 4 billion unique addresses (2³²), however, with over 7 billion people and countless devices per person, a solution was needed

IPv6

• Internet Protocol version 6 is represented as 8 blocks of 4 hexadecimal digits, separated by colons

• Each block is 2 bytes (16 bits), each address is 16 bytes (128 bits)

• IPv6 could provide over one billion unique addresses for every person on the planet (2¹²⁸)