IPv6 Subnet Calculator

What is an IPv6 address?

A 16-byte IPv6 address is normally represented hexadecimal digits and divided into 8 groups separated by colons (:). For example, "2001:0cb8:0000:0000:0000:ff00:0246:7348" IPv6 address.

An IPv6 address is a unique identifier assigned to devices connected to an Internet Protocol version 6 (IPv6) network. IPv6 is the latest version of the Internet Protocol, designed to replace IPv4 due to the depletion of available IPv4 addresses.

An IPv6 address consists of 128 bits, compared to 32-bit IPv4 addresses. It is represented as eight groups of four hexadecimal digits, separated by colons. For example, a typical IPv6 address might look like this: 2001:0db8:85a3:0000:0000:8a2e:0370:7334.

IPv6 addresses provide a significantly larger address space than IPv4, allowing for a virtually unlimited number of unique addresses. This expansion supports the growing number of devices connecting to the internet, including computers, smartphones, tablets, IoT devices, and more. IPv6 also offers additional features, such as improved security, auto-configuration, and better support for multicast communications.

IPv6 Examples

2002:c000:022a::/29
Address:     2002:c000:022a:0000:0000:0000:0000:0000/29
Netmask:     ffff:fff8:0000:0000:0000:0000:0000:0000 = 29
Network:     2002:c000:0000:0000:0000:0000:0000:0000/29
HostMin:     2002:c000:0000:0000:0000:0000:0000:0001
HostMax:     2002:c007:ffff:ffff:ffff:ffff:ffff:fffe
Hosts/Net:   633825300114114700748351602688 UNKNOWN
IPv4 repr:   192.0.2.42
PTR RR name: 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.a.2.2.0.0.0.0.c.2.0.0.2.ip6.arpa
IP version:  6

IPv6 Addresses

• 2001:0db8:1234:5678:9abc:def0:1234:5678
• fd12:3456:789a:1::2
• 2001:0:9d38:6abd:0:0:0:1
• 2409:8a61:3c0c:85::abcd:5678
• 2001:0db8::1:0:0:0:1
• fe80::1
• 2001:db8::
• 2a02:120b:2c0d:0010:0000:0000:0a0b:0304

IPv6 Subnet Chart

A quick reference for IPv6 Subnetting and Subnet masks.

What is CIDR?

CIDR, or Classless Inter Domain Routing, was created to help large routers minimize the size of their routing tables, which was complex with classful routing.

Classful routing consumes a lot of memory, resulting in prohibitively expensive hardware. However, performance was hampered because enormous tables had to be looked up without using a more dynamic IP interval technique, such as CIDR. Another issue with a classful system is that bandwidth utilization is rather significant when routers communicate routing information.

Simply put, CIDR with address aggregation allows numerous networks to be addressed with a single routing entry.