Computer Networks ip addressing


So I have this exercise in one of my classes on network ip addressing. The problem is that i cant figure out how to complete the subnet bits and hosts bits..can anyone help me?

the number of hosts is 414, 189, 135 and 90...

2 Answers: 

Subnetting works in binary, with # of hosts being "binary -2". 32 and 31 bit subnets are practically useless, so start with 30. It's basically just inversed, subnets to hosts. Observe:

Subnet     Subnets         Hosts/Subnet
30          4194304          2
29          2097152          6
28          1048576         14
27           524288         30
26           262144         62
25           131072        126
24            65536        254
23            32768        510
22            16384       1022
21             8192       2046
20             4096       4094
19             2048       8190
18             1024      16382
17              512      32766
16              256      65534
15              128     131070
14               64     262142
13               32     524286
12               16    1048574
11                8    2097150
10                4    4194302
 9                2    8388606
 8                1   16777214

So when you're asked for a subnet to hold a # of hosts, just find the next size up. I.E.: 414 hosts would go on a /23 subnet. So 23 subnet bits, 9 host bits (32 bits altogether in IPv4).

Hope it helps!!


This is a very basic and important question in IP addressing and I would ask you to go through the Chapter-19 of Data Communications and Networking by Forouzan(4th Edition).It will help you to learn even more in a very intuitive language.I hope this helps.


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