128. 15 . 4 .0
255.255.255.0
256 (254) addresses
128. 15 . 4 .0
255.255.254.0
512 (510) addresses
I Need Twice that Number of Addresses !
128. 15 . 4 .0
255.255.252.0
1024 (1022) addresses
128. 15 . 4 .0
255.255.248.0
2048 (2046) addresses
128. 15 . 4 .0
255.255.240.0
4096 (4094) addresses
128. 15 . 4 .0
255.255.224.0
8192 (8190) addresses
If you look at this in decimal it is like where are these numbers coming from?
So let's look at the subnet mask in Binary...
1111 1111 . 1111 1111 . 1111 1111 . 0000 0000
1111 1111 . 1111 1111 . 1111 1110 . 0000 0000
1111 1111 . 1111 1111 . 1111 1100 . 0000 0000
1111 1111 . 1111 1111 . 1111 1000 . 0000 0000
1111 1111 . 1111 1111 . 1111 0000 . 0000 0000
1111 1111 . 1111 1111 . 1110 0000 . 0000 0000