IPv6 Addressing

⭐ CCST GOLD LINE (Remember This First)

IPv6 = Bigger address space to replace IPv4

📌 IPv6 was created because IPv4 addresses are running out

🔢 What is IPv6 Addressing?

An IPv6 address is a 128-bit address used to identify devices on a network.

🧠 Compare:

IPv4 → 32 bits ❌ (limited)
IPv6 → 128 bits ✅ (huge)

👉 IPv6 can provide billions of addresses for every person on Earth 🌍

IPv6 – 128 Bit Address Space

✍️ IPv6 Address Format (Easy)

🔹 How IPv6 Looks

2001:0db8:85a3:0000:0000:8a2e:0370:7334

📌 Key points:

Written in hexadecimal (0–9, a–f)
8 groups (blocks)
Each block = 16 bits
Blocks separated by :

Basic IPv6 Address Structure

✂️ IPv6 Shortening Rules (VERY IMPORTANT)

Rule 1: Remove leading zeros
0db8 → db8

Rule 2: Replace continuous zeros with ::
2001:0db8:0000:0000:0000:0000:0000:0001
↓
2001:db8::1

📌 :: can be used only once in an address

🧩 IPv6 Address Types (VERY IMPORTANT FOR CCST)

🟦 1️⃣ Unicast Address

📌 One-to-one communication

🧠 Meaning: One sender → One receiver

Common Unicast Types

Global Unicast → Public IPv6 (internet-routable)
Link-Local → Local network only

🧠 Example:
2001:db8::10

👉 Similar to IPv4 public & private IP

🟩 2️⃣ Multicast Address

📌 One-to-many communication

🧠 Meaning: One sender → Multiple receivers

🧠 Example:
ff02::1

👉 Sends data to all devices in a group
📌 IPv6 uses multicast instead of broadcast

🟨 3️⃣ Anycast Address

📌 One-to-nearest (best) receiver

🧠 Meaning:

Same IPv6 address assigned to multiple devices
Data goes to the closest one

🧠 Examples:

DNS servers
CDN servers

👉 Improves speed & reliability

IPv6 Address Types

❌ What About Broadcast?

🚫 IPv6 has NO broadcast

📌 Broadcast is replaced by multicast

🧩 IPv6 Address Types (Summary Table)

Type	Communication	Example Use
Unicast	One → One	Web browsing
Multicast	One → Many	Routing updates
Anycast	One → Nearest	DNS, CDN
Broadcast	❌ Not used	Replaced by multicast

📍 IPv6 Prefix & Prefix Notation (CIDR Style)

An IPv6 prefix tells which part of the address is the network.

📌 Similar to subnet mask in IPv4
📌 Uses slash notation

🧠 Example:

2001:db8:abcd:0012::/64

👉 First 64 bits = Network
👉 Last 64 bits = Host

📌 /64 is the MOST COMMON prefix in IPv6

Common IPv6 Prefix Lengths

Prefix	Meaning	Usage
/64	Standard subnet	LAN networks
/48	Large organization	ISP allocation
/128	Single device	Loopback

📌 CCST Tip: If you see IPv6 → assume /64

🧠 IPv4 vs IPv6 (Quick Comparison)

Feature	IPv4	IPv6
Address size	32-bit	128-bit
Format	Decimal	Hexadecimal
NAT needed	✅ Yes	❌ No
Broadcast	✅ Yes	❌ No
Multicast	Limited	Built-in

IPv4 vs IPv6 Comparison

🛠️ CCST Troubleshooting Examples

Symptom	Likely Cause
Device has IPv6 but no internet	Gateway / prefix issue
Neighbor discovery fails	Link-local issue
Network flood	Wrong multicast config

🧠 Memory Tricks (Exam Gold 🥇)

IPv6 = Big address
No broadcast
/64 is standard
:: = compressed zeros
Unicast, Multicast, Anycast