IP addressing (Cambridge International AS Computer Science)

IP addressing

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 are dynamic, 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)

Subnetting

• Subnetting is the process of dividing a larger network into smaller, more manageable parts, called subnets (short for sub-networks)

• Each subnet works like a mini-network within the main network, allowing devices to communicate more efficiently

• Benefits of subnetting include:

  • Reduces network traffic – less data is broadcast across the whole network
  • Improves speed and performance – data stays within its local subnet
  • Increases security – limits access so not all devices can reach all parts of the network
  • Easier to manage and maintain – changes can be made to one subnet without affecting the rest
  • Improves organisation – helps group devices by department or function

• It's commonly used in larger networks, like schools or businesses, to reduce traffic, keep data local, and make management easier

Public vs private IP addresses

• Public IP addresses are assigned to devices that need a constant connection to the internet

• Examples:

  • Web servers
  • Email servers

• Globally unique – no two devices can have the same public IP

• Allows devices to be directly accessed from anywhere on the internet

• Private IP addresses are assigned to devices on a Local Area Network (LAN) by a router

• Not routable on the internet – improves network security

• Used for items in a home or office, such as:

  • Laptops
  • Phones
  • Printers

• Allows internal communication without exposing devices to the public internet

Static vs dynamic IP addresses

• Static IP addresses are fixed IP addresses that do not change

• Assigned to devices that need a consistent address Commonly used for:

  • Websites
  • Remote access services
  • Email or file servers

• No management required once set

• Allows reliable access from anywhere on the network or internet

• Dynamic IP addresses are temporarily assigned when a device connects to the network

• Comes from a pool of available IP addresses

• Managed automatically by a DHCP server (Dynamic Host Configuration Protocol)

• Ideal for devices where a fixed address isn't needed

  • e.g. laptops, smartphones, or guest devices

Worked Example Computers on the Internet have IP addresses.

Describe the format of an IP address. [3]

Final answer: Answer

**IPv4 **

• Four groups of denary or hexadecimal digits** [1 mark]**
• Numbers between 0 and 255 / 0 and FF [1 mark]
• Each is stored in 1 byte / 8 bits [1 mark]
• The whole number is stored in 32 bits / 4 bytes [1 mark]
• Separated by full stops [1 mark]
• Correct example [1 mark]

OR

**IPv6 **

• Eight groups of (Hexadecimal) digits** [1 mark]**
• Numbers between 0 and FFFF [1 mark]
• Each is stored in 2 bytes/16 bits [1 mark]
• The whole number is stored in 128 bits / 16 bytes [1 mark]
• Separated by colons [1 mark]
• The first instance of multiple groups of zero can be replaced by a double colon [1 mark]
• Correct example [1 mark]