Lesson 2.13: IPv6: the next generation of addresses
Why IPv6 exists, what a 128-bit address looks like and how to shorten it, prefixes, the special addresses (loopback ::1, link-local fe80::, global unicast, documentation 2001:db8::), how devices give themselves addresses (SLAAC), dual stack, and what IPv6 changes for security. In the lab you find your IPv6 addresses, reach the loopback and your own link-local address, see how that address was built from your MAC, and look up a server's IPv6 address in DNS.
17 min
You will learn to
- Explain why IPv6 was created
- Write and shorten an IPv6 address
- Recognise loopback, link-local, global and documentation addresses
- Explain SLAAC and dual stack
- Name what IPv6 changes for security
Key terms
- IPv6
- Version 6 of the Internet Protocol, with 128-bit addresses: about 3.4 × 10³⁸ of them.
- IPv6 address notation
- Eight groups of four hexadecimal digits separated by colons. Leading zeros in a group can be dropped, and one run of all-zero groups can be replaced by ::.
- Prefix
- The network part of an IPv6 address, written with a length like IPv4 CIDR. A normal network (subnet) is a /64.
- Link-local address
- An address starting with fe80:: that every IPv6 interface gives itself, valid only on its own network segment and never routed.
- Global unicast address
- A public IPv6 address, reachable across the internet. Today these start with 2 or 3.
- SLAAC
- A device builds its own address from the prefix the router announces plus an identifier it chooses, without a DHCP server.
- Dual stack
- Running IPv4 and IPv6 side by side on the same device or network.
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