Computing - Don't forget your ZERO

This is one of those concepts that causes confusion in various areas, but particularly those learning about networking. We think that counting should start at 1, this is what we're taught from the minute we're introduced to numbers. "0" means "Nothing to see here", right? Not in computing...

It helps if you can think of the numbers as objects instead. Try this:

You have 64 total objects, pretend they're wooden blocks, and they have the numbers 0-63 stamped on them. Now, you know that no matter what's on the blocks, there are still 64 total blocks. You could line them up on the floor in sequence and count them and the 7th block over would have a 6 stamped on it, but it's still the 7th block.

This is very much how it works in computing. The zero space is the first space, not the "null" space (null means "nothing to see here", it's a non-object). Another way to look at it is that we're using the numbers as labels for objects.

Check out my pretty picture of blocks over there. Notice that the sequence is 1, 9, 0, 1, 2, 3, etc. We can look at the blocks and count, left to right top to bottom, three blocks. The third block is actually a 1, but we don't think it's the first block. We know that it's the third block in the sequence, it just happens to be labeled "1". Same with numbering when it comes to computers, it's the first object or memory space or what-have-you, but the label is "0", and it's important to remember the labels.

WARNING: Slightly more technical, this is specifically about networking.

In a networking scenario the same rule applies, you have to start at 0. Normally the 0 address is the "subnet address" so we never see it applied as a standard IP address, but this gets more complicated when you start doing subnetting and determining the address space in subnets. The address space may be 64 in a /26 subnet, but the address space is not 1-64, it's 0-63, making the next subnet the .64 subnet.