Identifying Devices (Edexcel IGCSE ICT)

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 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

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

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