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Class B Network |
Class B:
255.255.xxx.yyy
xxx : from 0 to 255
yyy : from 0 to 255
We mask as follows:
-- As in class C.0,, that is we vary xxx and we fix yyy
255.255.0.0
255.255.128.0
255.255.192.0
255.255.224.0
255.255.240.0
255.255.248.0
255.255.252.0
255.255.254.0
And
As the class C, that is we fix xxx = 255 and we vary yyy
255.255.255.0
255.255.255.128
255.255.255.192
255.255.255.224
255.255.255.240
255.255.255.248
255.255.255.252
We do not vary xxx and yyy at the same time.
But
Subnet Bits: Number of bits masked (equal to 1)
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Class B Formulas:
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IP Address:xxx.yyy.zzz.vvv
where the First Octet Range xxx's is: 128 - 191.
and the Second, third and fourth Octet Range is: 0 - 255
Mask : One of the elemnts of the following array:
In decimal: [M] = {128, 192, 224, 240, 248, 252, 254, 255}
In binary: [M] = {10000000, 11000000, 11100000, 11110000, 11111000, 11111100, 11111110, 1111111}
Subnet Bits = the number of 1 in binary's representation of the Mask
Subnet Mask: 255.255.m.0 and 255.255.255.m (m belongs to [M])
Max Subnet = 2Subnet Bits
Number of Hosts = (256 - Mask) x 256 - 2
- 2 stands for that we reseve the first and the last host addresses: The first is called
Subnet ID, the second Broadcast Address
Subnet ID = xxx.yyy.0.0
Broadcast Address: xxx.yyy.(255 - Mask). (255 -Mask)
Wildcard Mask:
0.0.(255 - Mask).255
Host Address Range:
xxx.yyy.0.1 - xxx.yyy.(255 - Mask).254
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Subnet Mask Subnet Max
Bits Subnet Hosts
0 255.255.0.0 Subnet Bits = 0 Max Subnet = 1 Hosts = 256 x 256 - 2 = 65534
1 255.255.128.0 Subnet Bits = 1 Max Subnet = 2 Hosts = 128 x 256 - 2 = 32766
2 255.255.192.0 Subnet Bits = 2 Max Subnet = 4 Hosts = 64 x 256 - 2 = 16382
3 255.255.224.0 Subnet Bits = 3 Max Subnet = 8 Hosts = 32 x 256 - 2 = 8190
4 255.255.240.0 Subnet Bits = 4 Max Subnet = 16 Hosts = 16 x 256 - 2 = 4094
5 255.255.248.0 Subnet Bits = 5 Max Subnet = 32 Hosts = 8 x 256 - 2 = 2046
6 255.255.252.0 Subnet Bits = 6 Max Subnet = 64 Hosts = 4 x 256 - 2 = 1022
7 255.255.254.0 Subnet Bits = 7 Max Subnet = 128 Hosts = 2 x 256 - 2 = 510
And
As the class C
8 255.255.255.0 Subnet Bits = 8 Max Subnet = 256 256 - 2 = 254
9 255.255.255.128 Subnet Bits = 9 Max Subnet = 512 128 - 2 = 126
10 255.255.255.192 Subnet Bits = 10 Max Subnet = 1024 64 - 2 = 62
11 255.255.255.224 Subnet Bits = 11 Max Subnet = 2048 32 - 2 = 30
12 255.255.255.240 Subnet Bits = 12 Max Subnet = 4096 16 - 2 = 14
13 255.255.255.248 Subnet Bits = 13 Max Subnet = 8192 8 - 2 = 6
14 255.255.255.252 Subnet Bits = 14 Max Subnet = 16384 4 - 2 = 2
Subnet ID Example: 172.32.0.0
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From 0 - 7:
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Hosts = (256 - Mask) x 256 - 2
Mask: 0
Broadcast Address: 172.32.255.255
0 + 255 = 255
Host Address Range: 172.32.0.1 - 172.32.255.254
Mask: 128
Broadcast Address: 172.32.127.255
128 + 127 = 255
Host Address Range: 172.32.0.1 - 172.32.127.254
Mask: 192
Broadcast Address: 172.32.63.255
192 + 63 = 255
Host Address Range: 172.32.0.1 - 172.32.63.254
Mask: 224
Broadcast Address: 172.32.31.255
Wildcard Mask: 0.0.31.255
224 + 31 = 255
Host Address Range: 172.32.0.1 - 172.32.31.254
Mask: 240
Broadcast Address: 172.32.15.255
Wildcard Mask: 0.0.15.255
240 + 15 = 255
Host Address Range: 172.32.0.1 - 172.32.15.254
Mask: 248
Broadcast Address: 172.32.7.255
Wildcard Mask: 0.0.7.255
248 + 7 = 255
Host Address Range: 172.32.0.1 - 172.32.7.254
Mask: 252
Broadcast Address: 172.32.3.255
Wildcard Mask: 0.0.3.255
252 + 3 = 255
Host Address Range: 172.32.0.1 - 172.32.3.254
Mask: 254
Broadcast Address: 172.32.1.255
Wildcard Mask: 0.0.1.255
254 + 1 = 255
Host Address Range: 172.32.0.1 - 172.32.1.254
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From 8 - 15 :
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Hosts = (256 - Mask) - 2
Mask: 0
Broadcast Address: 172.32.0.255
0 + 255 = 255
Host Address Range: 172.32.0.1 - 172.32.0.254
Mask: 128
Broadcast Address: 172.32.0.127
128 + 127 = 255
Host Address Range: 172.32.0.1 - 172.32.0.126
Mask: 192
Broadcast Address: 172.32.0.63
192 + 63 = 255
Host Address Range: 172.32.0.1 - 172.32.0.62
Mask: 224
Broadcast Address: 172.32.0.31
224 + 31 = 255
Host Address Range: 172.32.0.1 - 172.32.0.30
Mask: 240
Broadcast Address: 172.32.0.15
240 + 15= 255
Host Address Range: 172.32.0.1 - 172.32.0.14
Mask: 248
Broadcast Address: 172.32.0.7
248 + 7 = 255
Host Address Range: 172.32.0.1 - 172.32.0.6
Mask: 252
Broadcast Address: 172.32.0.3
252 + 3 = 255
Host Address Range: 172.32.0.1 - 172.32.0.2
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