This algorithm is illustrated.
Example: Given a Class C Address: 192.168.5.0, required to divide 20 subnets, each subnet 5
Host.
Solution: Because 4 <5 <8, use 256-8 = 248 ->, the number of subnet masks, the corresponding subnet
Then there will be it. This is for C-class addresses. Teachers also only talked about the practice of Class C. Here is my own
It is pushed out for B-class addresses.
For class B addresses, if the number of hosts is less than or equal to 254, the same is the same as the C class address algorithm.
For the number of hosts than 254, if you need 700 hosts, 50 subnets (quite big),
512 <700 <1024
256- (1024/256) = 256-4 = 252 -> That is, the subnet mask of the sought, the corresponding subnet number
Out.
4 (2 power of 2) above 256-4 means that the number of bits of the host number of 2 binders, that is, more than
2, mask is the remaining top 6, namely 2 (6) -2 = 62.
Welcome to correct.
Append: host / subnet quantities TABLE
-------------------------------------------------- --------------------
------------
Class A Effective Effective
# BITS MASK SUBNETS HOSTS
-------------------------------------
2 255.192.0.0 2 4194302
3 255.224.0.0 6 2097150
4 255.240.0.0 14 1048574
5 255.248.0.0 30 524286
6 255.252.0.0 62 262142
7 255.254.0.0 126 131070
8 255.255.0.0 254 65536
9 255.255.128.0 510 32766
10 255.255.192.0 1022 16382
11 255.255.224.0 2046 8190
12 255.255.240.0 4094 4094
13 255.255.248.0 8190 2046
14 255.255.252.0 16382 1022
15 255.255.254.0 32766 510
16 255.255.255.0 65536 254
17 255.255.255.128 131070 126
18 255.255.255.192 262142 62
19 255.255.255.224 524286 30
20 255.255.255.240 1048574 1421 255.255.255.248 2097150 6
22 255.255.255.252 4194302 2
Class B Effective Effective
# BITS MASK SUBNETS HOSTS
-------------------------------------
2 255.255.192.0 2 16382
3 255.255.224.0 6 8190
4 255.255.240.0 14 4094
5 255.255.248.0 30 2046
6 255.255.252.0 62 1022
7 255.255.254.0 126 510
8 255.255.255.0 254 254
9 255.255.255.128 510 126
10 255.255.255.192 1022 62
11 255.255.255.224 2046 30
12 255.255.255.240 4094 14
13 255.255.255.248 8190 6
14 255.255.255.252 16382 2
Class C EFFECTIVE EFFECTIVE
# BITS MASK SUBNETS HOSTS
-------------------------------------
2 255.255.255.192 2 62
3 255.255.255.224 6 30
4 255.255.255.240 14 14
5 255.255.255.248 30 6
6 255.255.255.252 62 2
* Subnet All Zeroes and all ones Excluded.
* Host All Zeroes and all ones excluded.
