What three categories of IPv6 address exist, and which IPv4 concept is notably missing?
Unicast (one destination), multicast (a group), and anycast (the nearest member of a group) — there is no broadcast in IPv6.
| Type | Delivered to | IPv4 analogue |
|---|---|---|
| Unicast | exactly one interface | unicast |
| Multicast | all members of a group | multicast |
| Anycast | the nearest one member of a group (by routing) | (none) |
The big change: broadcast is gone. In IPv4, broadcasts (sending to everyone on the subnet) are noisy and waste CPU on every host. IPv6 abolishes broadcast entirely and replaces it with targeted multicast groups — e.g. "all routers" instead of "literally everyone."
Anycast is clever: many servers share the same address, and the network routes you to whichever is closest. This is how root DNS servers and CDNs achieve redundancy and load distribution.
Tip: Unicast = one phone call, multicast = a group chat, anycast = dialling a hotline that connects you to your nearest branch.
Go deeper:
IPv6 address (Wikipedia) — the unicast / multicast / anycast classification with diagrams, plus why broadcast was dropped.