IPv6 Addresses and Subnets

There’s a basic problem with IPv4: It provides only 4.29 billion addresses, and that’s just not enough. Without subnetting, that’s fewer than one address for every human being. Eventually, every person will have at least one IP-capable device.

Although IPv4 addresses haven’t run out yet, they’re becoming an increasingly scarce resource. Overly generous allocations in the early days, along with large chunks of address space reservations for special purposes, have accelerated exhaustion. The world is slowly grinding toward IPv4’s replacement: IPv6.

Some parts of the world already use IPv6 extensively. Even if your network doesn’t use IPv6 today, one day you’ll need it—probably without warning. Prepare yourself now, or ...

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