I'm not gonna kid ya, the site is really ugly, but it gets the job done. Just remeber we're dealing with Networkers here not programmers or artists. But for all intestive purposes this is the best tutoral I've ever seen on Subnetting. There's alot of other good stuff at this site too, but I haven't gotten a chance to look at it yet.
One of the best sites I've seen related to Networking. The information is accurate and its presented in an easy to follow way. The site layout may leave something to be desired, and I have a few minor suggestions for the navigation, but as far as content goes this site definitely scores high marks. And as we all know, content is king.
And here's the 2 cent tutorial for 'subnets' curtesy to Tyberius Prime:
[i]The subnetmask tells a computer what IPs it can reach directly. For all other IPs it needs to have a valid route over a router, to reach them.
They are set pretty simple... All bits that belong to your net are set to one.
So a subnet mask of 255.255.255.0 means that anything where just the last 8 bits are different is in your subnet -> no router needed. 255.255.0.0 means that the last 16 bits may change, and you're still in your subnet. And so on. 0.0.0.0 then matches every internet address. 255.255.255.255 only matches exactly one address.
These days, there are quite a few 'broken' subnets, like 255.255.128.0. Turn them into bits, and you'll know what can differ.
An alternative way to write subnets is the /bits syntax. so IP/16 would mean a netmask of 255.255.0.0, and IP/24 would mean 255.255.255.0 (remember, 8 bits => one byte => one part of an ip.
LearntoSubnet™.com - a number of lectures (slides and the spoken overview) that runs you through the whole thing. It is one of the best resources I have yet found with plenty of practical examples. If you don't get subnetting after going through these lectures then you are doomed.
