Identifying Devices (Edexcel IGCSE Ict)

IP Addresses

Spec point — 2.3.1

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 allocated by a network administrator or assigned dynamically by a Dynamic Host Configuration Protocol server (DHCP)
• 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)

MAC Addresses

Spec point — 2.3.1

What is a MAC address?

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

• MAC addresses can be used to:

  • Restrict or allow access to a network
  • Identify a device on a network
  • Track a device
  • Assign 'static' or 'fixed' IP addresses

Device name

Spec point — 2.3.1

What is a device name?

• A device name is a way for users to describe/name a device so that it is easier to identify on a network
• Device names are not used by devices to communicate as they are not always unique
• Device names are set by users in the devices operating system or from a router

Worked Example Computers in a network can be identified using both IP addresses and MAC addresses.

Describe two differences between IP addresses and MAC addresses

[2]

Answer

• IP address is dynamic/can change // MAC address is static/cannot change [1]
• IP address is used to communicate on a WAN/Internet // MAC address is used to communicate on a LAN [1]