WHY CAN A ROUTER CONNECT TO A MAXIMUM OF 255 DEVICES?
You may think that 255 devices sounds like an arbitrary cap, but there’s a good reason (and a long history) behind it. If you were to break down a computer (of which a router is just a specialised example) to its fundamental components you’d see that it’s simply a collection of switches. Each can be on or off, and those states can be represented using the numbers one (for on) or zero (for off). These same digits are used in the binary counting system.
But binary isn’t easy for humans to work with, in part because it quickly gets much longer than decimal equivalents. For example, 86 is 1010110 in binary.
To make things less complicated, we break down these long strings of numbers into groups of eight, which we call ‘octets’ or bytes. Each of the eight ones and zeros that make up a byte is called a ‘bit’. Everything your computer does is based on bytes, and the binary ones and zeroes (bits) that make them up. When you save a file, it’s converted to and written as a string of bits, then converted back into a copy of your original document the next time you open it.
Likewise, when you connect a device to your router, it’s given a binary address, so the router knows where it’s receiving data from, and which device it’s sending data to. This address is converted to a decimal number in the router’s configuration screens (see screenshot right), as well as by Windows, Android and IOS, to make it easier for us to understand.
Engineers working on the earliest networks probably never imagined we’d have as many connected devices as we now take for granted, so they assigned a single byte’s-worth (eight digits) of slots (or addresses) for each group of connected devices. But how many is that?
Remember, a byte is made up of eight bits (or binary numbers), and each bit can have two states – one or zero. So, to work out how many devices can be accommodated in a single group on a device like a router, we multiply two (the number of states for each slot) by the power of eight (the number of bits – or slots – in a byte). When written out, this would be 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2, the answer to which is 256. One connection is reserved for the router itself so, unless you fiddle with your network configuration, you have a theoretical maximum of 255 empty slots to host other devices.