1.2 · IPv4 & IPv6 Addressing

Goal: explain the format and reason-for-being of both addressing schemes.

What an IP address does

Every device on a network needs a unique address so that data can find its way. The Internet Protocol (IP) defines this address.

Example breakdown:

192.168.1.10
└┬┘ └┬┘ │ └┬┘
 │   │  │  └─ host part
 │   │  └──── 
 │   └─────── 
 └─────────── network parts

A simplified mental model: "Every grain of sand on Earth could have its own IPv6 address several times over."

IPv4 ran out of unique addresses globally (officially announced exhausted in 2011 by IANA).
IoT (billions of devices) demands far more addresses than IPv4 can provide.
IPv6 has simpler routing, built-in security extensions, no need for NAT.

DHCP (Dynamic Host Configuration Protocol) — most home routers hand out IP addresses automatically.
Static IP — manually assigned (typically for servers and printers).
APIPA / Link-local — automatic fallback if DHCP fails.

Public IPs are unique on the global Internet.
Private IPs are reused inside LANs; NAT (Network Address Translation) on the router translates between them.

Technical details not required by C&A

The syllabus says "technical details are not required". Focus on purpose, format and reason for transition.

Q (4 marks): State two differences between IPv4 and IPv6, and give one reason IPv6 is being introduced.

Sample answer:

Length: IPv4 is 32 bits, IPv6 is 128 bits.
Notation: IPv4 uses dotted decimal (192.168.1.1); IPv6 uses colon hexadecimal (2001:db8::1).
Reason for IPv6: IPv4 only supports ~4.3 billion unique addresses, which were exhausted as the number of Internet-connected devices grew (smartphones, IoT). IPv6 provides 2¹²⁸ addresses, enough for the foreseeable future.