Describe the structure of an IPv6 address and three key benefits over IPv4.

• A. 128-bit address, hex notation, benefits: massive space, simplified header, built-in autoconfiguration, no NAT required.
• B. 64-bit address, decimal notation, benefits: smaller routing tables, requires NAT.
• C. 128-bit address, binary notation, benefits: faster CPUs, manual address assignment, universal encryption.
• D. 96-bit address, octal notation, benefits: reduced header, no need for routing protocol.

Answer: (A)

IPv6 addresses are 128 bits long and are written in hexadecimal as eight groups of four digits, separated by colons. This enables a hierarchical structure that typically places a global routing prefix in the first halves and an interface identifier in the last half, often using a 64-bit prefix and a 64-bit interface ID. Addresses can be shortened by omitting leading zeros and collapsing consecutive zero groups with a double colon representation, which keeps them readable while preserving the full 128-bit value.

Three main advantages over IPv4 stand out. First, the enormous address space (2^128) eliminates the need for complex workarounds like NAT for most scenarios, enabling abundant unique addresses for devices. Second, the header is simplified and fixed in length, which speeds up processing by routers and improves efficiency in packet handling. Third, built-in autoconfiguration lets devices configure themselves automatically (via SLAAC or DHCPv6), simplifying network setup and management while maintaining end-to-end connectivity. These factors together explain why IPv6 is designed to be easier to configure, more scalable, and more straightforward to route than IPv4.