IP addressing

• Subnetting is the procedural method of dividing a large network into smaller, manageable logical segments called subnets.

• This process improves network performance by reducing broadcast traffic, as data packets intended for a specific local group do not need to be sent across the entire global network.

• Subnetting also enhances security by allowing administrators to apply different access rules to different subnets, effectively isolating sensitive parts of the network.

Public vs Private IP Addresses

• Public IP addresses are globally unique and are used to identify devices directly on the Internet. They are assigned by Internet Service Providers (ISPs) and are routable across the global web.
• Private IP addresses are used within a Local Area Network (LAN) and are not routable on the Internet. This allows multiple devices in a home or office to share a single public IP address via a router.

Static vs Dynamic IP Addresses

• Validation Check: When identifying valid IPv4 addresses, always ensure no number in the four blocks exceeds 255. Any value outside the range $0-255$ is mathematically impossible for an 8-bit field.

• Format Recognition: Remember that IPv4 uses dots and denary, while IPv6 uses colons and hexadecimal. Mixing these formats is a common distractor in multiple-choice questions.

• DHCP Role: Always associate dynamic IP assignment with the DHCP (Dynamic Host Configuration Protocol) server. If a question asks how a laptop gets an IP without manual setup, DHCP is the answer.

• Security Logic: If asked why private IPs are used, focus on the fact that they are 'not routable' on the internet, which acts as a natural barrier against external attacks.