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Networking Fundamentals · Foundational

Global Unicast Address (GUA)

A globally routable IPv6 address, currently allocated from 2000::/3.

Definition

GUAs are the IPv6 equivalent of public IPv4 addresses. A typical structure is a 48-bit global routing prefix assigned to a site, a 16-bit subnet ID, and a 64-bit interface ID. Addresses can be assigned statically, by SLAAC, or by DHCPv6.

Example

2001:db8:cafe:1::10/64 is in the global unicast format (2001:db8::/32 is reserved for documentation).

Exam tip

Addresses beginning with 2 or 3 are global unicast; fe80 is link-local; fc or fd is unique local.

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