IPv6 Addressing
IPv6 addressing schemes
What you will learn
- Write an IPv6 address in correct shortened notation.
- Distinguish the three IPv6 address types: unicast, multicast, anycast.
- Explain why IPv6 has no broadcast.
- Recall the link-local address format.
An IPv6 address is written as eight groups of four hexadecimal digits, separated by colons (e.g., 2001:0db8:0000:0000:0000:ff00:0042:8329). Writing it in full is tedious, so the rules allow two shortcuts: dropping leading zeros within each group, and replacing one single consecutive run of all-zero groups with `::`, only once per address.
Shortening an IPv6 address — example
1. Full address
2001:0db8:0000:0000:0000:ff00:0042:8329
2. Drop leading zeros in each group
2001:db8:0:0:0:ff00:42:8329
3. Replace the consecutive zero groups with ::
2001:db8::ff00:42:8329
IPv6 address types
| Unicast | A single specific device's address — like regular IPv4. |
|---|---|
| Multicast | Sends to a group of registered interested devices only — partially replaces broadcast. |
| Anycast | Sends to the nearest device among a group sharing the same address — has no IPv4 equivalent. |
| Link-local | An address valid only within the same local segment, always starting with fe80::. |
Common confusion
IPv6 has no broadcast address at all — this isn't a gap, it's a design decision: IPv4 broadcast reaches every device even if uninterested, wasting network resources. IPv6 replaces it with multicast, which reaches only devices that actually registered interest.
Quick check
Answer in your head first, then reveal.
How many hex groups in a full IPv6 address?Reveal the answer
Eight groups.
What prefix do link-local addresses start with?Reveal the answer
fe80::
Which address type has no IPv4 equivalent?Reveal the answer
Anycast.
Sign in to track your progress on this topic.
Your next step
Read the lesson, then mark it complete
Sources
Used to verify the facts. The writing is original to Passuit.