IPv6 (Internet Protocol version 6) is the successor to IPv4. It was developed to overcome the limited address space of IPv4 while simplifying many aspects of Internet routing and network configuration.
An IPv6 address is 128 bits long, providing an extremely large number of unique addresses.
Example:
2001:db8:85a3::8a2e:370:7334
Today, IPv6 is increasingly deployed alongside IPv4 across the Internet.
IPv4 uses 32-bit addresses, allowing approximately:
2^32 = 4.3 billion addresses
As the Internet grew, this address space became insufficient.
IPv6 was introduced to provide:
An IPv6 address contains 128 bits, written as eight groups of four hexadecimal digits.
Example:
2001:0db8:85a3:0000:0000:8a2e:0370:7334
Each group represents 16 bits.
Hexadecimal digits use:
0-9 A-F
IPv6 provides rules that make addresses easier to read.
Leading zeros may be omitted:
2001:0db8:0000:0000:0000:0000:0000:0001 ↓ 2001:db8:0:0:0:0:0:1
One consecutive sequence of zero groups may be replaced by “::”
2001:db8:0:0:0:0:0:1 ↓ 2001:db8::1
The “::” shortcut may appear only once in an IPv6 address.
IPv6 provides:
2^128 ≈ 340 undecillion addresses
This number is so large that IPv6 effectively eliminates address exhaustion for the foreseeable future.
| Prefix | Purpose |
|---|---|
| 2000::/3 | Global Unicast |
| fc00::/7 | Unique Local Addresses (ULA) |
| fe80::/10 | Link-Local Addresses |
| ::1 | Loopback |
| :: | Unspecified Address |
These are publicly routable on the Internet.
Example:
2001:4860:4860::8888
These are similar to private IPv4 addresses.
Example:
fd12:3456:789a::1
They are intended for use within private networks.
Every IPv6-enabled interface automatically receives a link-local address.
These addresses begin with:
fe80::
They are used for communication within the local network segment and are never routed across the Internet.
One major difference from IPv4 is that IPv6 generally provides enough addresses for every device to have its own globally unique address.
Therefore, Network Address Translation (NAT) is usually unnecessary.
This simplifies end-to-end communication.
| IPv4 | IPv6 |
|---|---|
| 32 bits | 128 bits |
| Decimal notation | Hexadecimal notation |
| About 4.3 billion addresses | Vast address space |
| NAT commonly used | NAT usually unnecessary |
| Broadcast supported | No broadcast (uses multicast instead) |
Many modern networks support both IPv4 and IPv6 simultaneously.
This is known as Dual Stack.
Example:
IPv4 203.0.113.25 IPv6 2001:db8::25
A device may communicate using either protocol depending on network availability.
IPv6 supports Reverse DNS using the ip6.arpa namespace.
Example:
2001:db8::1 ↓ ...ip6.arpa
Reverse DNS is implemented using PTR records, just as with IPv4.
Several Telenegar tools support IPv6 addresses.
These tools can display information such as:
ipv6 ip internet networking ip6 dual-stack