How is an IPv6 address structured and represented?

128 bits written as 8 hextets (groups of 4 hex digits = 16 bits each) separated by colons, e.g. 2001:0db8:acad:0001:0000:0000:0000:0001.

IPv6 Address Structure:

IPv6 Format:

• 128 bits divided into 8 groups of 16 bits each
• Each group called a hextet (or quartet)
• Separated by colons (:)
• Uses hexadecimal (0-9, a-f)

Example breakdown:

2001:0db8:acad:0001:0000:0000:0000:0001
|    |    |    |    |    |    |    |
Hextet 1  2    3    4    5    6    7    8

Key insight: Each hextet = 4 hex digits = 16 bits

Go deeper:

• RFC 4291 §2.2 — Text Representation of Addresses — the authoritative definition of the x:x:x:x:x:x:x:x hex-colon notation.
• IPv6 address (Wikipedia) — 128-bit structure, hextets and the canonical representation rules with worked examples.