Block |
Netmask |
# of Nets |
# of Hosts |
/32 |
255.255.255.255 |
1/256 of a C |
1 |
/31 |
255.255.255.254 |
1/128 |
2 |
/30 |
255.255.255.252 |
1/64 |
4 |
/29 |
255.255.255.248 |
1/32 |
8 |
/28 |
255.255.255.240 |
1/16 |
16 |
/27 |
255.255.255.224 |
1/8 |
32 |
/26 |
255.255.255.192 |
1/4 |
64 |
/25 |
255.255.255.128 |
1/2 |
128 |
/24 |
255.255.255.0 |
1 C |
256 |
/23 |
255.255.254.0 |
2 C's |
512 |
/22 |
255.255.252.0 |
4 C's |
1,024 |
/21 |
255.255.248.0 |
8 C's |
2,048 |
/20 |
255.255.240.0 |
16 C's |
4,096 |
/19 |
255.255.224.0 |
32 C's |
8,192 |
/18 |
255.255.192.0 |
64 C's |
16,384 |
/17 |
255.255.128.0 |
128 C's |
32,768 |
/16 |
255.255.0.0 |
1 B |
65,536 |
/15 |
255.254.0.0 |
2 B's |
131,072 |
/14 |
255.252.0.0 |
4 B's |
262,144 |
/13 |
255.248.0.0 |
8 B's |
512,000 |
The /N is a way of saying the assinging people designate the first n bits, and whoever bought them gets to designate the ending 32-n bits. The old way to refer to networks was class a class b and class c. Essentially .. class a would be a /8 (which no longer exists, buy a bunch of /13's). a class B would be a /16 and a class c is a /24 there were other rules (which I am learning in my CCNA class) that determined which numbers that the networking gods would assign to various 'classes' of networks. Basically any bits past the ones they assign you are yours to do with as you please.
The /n system really makes it much more convinient to buy the ammounts of IP's you need. It was like haveing a single serving, 10 server and 400 servering box of uh munchie puffs. Now you can buy however many ounces you need!
After I figured out what the heck the /n system meant (I think) I wrote it up here. thats what wiki is all about right?
Drunken ramblings by ColinDabritz