IPv4 uses 32-bit addresses, whereas IPv6 uses 128-bit addresses. IPv6 therefore provides vastly more unique addresses and introduces a simplified packet header, but both protocols identify devices and support the routing of packets across networks.
The Reasoning
An Internet Protocol address identifies a network interface so that routers can forward packets towards the correct destination. IPv4 and IPv6 perform this same core function, but they use different address formats and packet structures.
IPv4 provides , or approximately 4.3 billion, possible addresses. An IPv4 address is written as four decimal values separated by dots, such as 192.168.1.10.
IPv6 provides possible addresses. It uses eight groups of hexadecimal digits separated by colons, such as 2001:0db8:0000:0000:0000:ff00:0042:8329. Consecutive groups of zeros can be compressed once using ::.
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address length | 32 bits | 128 bits |
| Address capacity | ||
| Notation | Dotted decimal | Colon-separated hexadecimal |
| Base header size | 20-60 bytes | Fixed at 40 bytes |
| Broadcast | Supported | Replaced by multicast and anycast |
| Fragmentation | Routers or sending host may fragment packets | Only the sending host fragments packets |
| Address configuration | Manual configuration or DHCP | Supports manual configuration, DHCPv6 and stateless address autoconfiguration |
IPv4 address scarcity encouraged widespread use of Network Address Translation (NAT), where multiple private devices share one public address. IPv6 reduces this need because its address space is extremely large.
A common misconception is that IPv6 is automatically more secure. IPv6 supports IPsec, but security still depends on correct configuration, authentication, encryption and network management.
Exam Technique
For an IB Computer Science comparison, state the shared purpose first, then give paired differences: address length, notation, capacity and header handling. Do not merely write that IPv6 is “newer” or “faster”; explain the technical feature and its consequence for data transmission.
