Chapter 5. DNS and IPv6

While IPv6 provides many improvements in network management, one of the major driving forces behind its design was to greatly increase address space. An IPv4 address uses 32 bits, whereas an IPv6 address uses 128 bits. IPv6 is theoretically capable of providing many millions of IP addresses for every human on the planet!

The original IETF specifications for IPv6 date from 1995 but the Classless Inter-Domain Routing and Network Address Translation (see the sidebar "IPv4 Addresses and CIDR" in Chapter 3) initiatives of the mid-90s effectively postponed the urgent need for additional address space. Until very recently IPv6 usage was largely confined to experimental networks such as the IETF's 6bone ( and large ...

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