Tag Archives: internet

Divide an IPv4 address into a network and host portion. (Quick overview)

If an organization has lots of computers, or if its computers are geographically spread, it’s a good idea to divide its netwerk into smaller ones (subnets) connected by routers. The benefit of using subnets are less traffic (most traffic will stay on the local netwerk) and easier to isolate and identify a network problem.

The subnet mask splits an IPv4 address into a network and a host portion.

In this table below you can see how you can split your subnets using a subnet mask.

binary   subnet mask decimal subnet mask Mask Bits nodes per subnet
1 0.0.0.0 /1 2147483648
11 128.0.0.0 /2 1073741824
111 192.0.0.0 /3 536870912
1111 224.0.0.0 /4 268435456
1111.1 248.0.0.0 /5 134217728
1111.11 252.0.0.0 /6 67108864
1111.111 254.0.0.0 /7 33554432
CLASS A
1111.1111 255.0.0.0 /8 16777214
1111.1111 1 255.128.0.0 /9 8388606
1111.1111 11 255.192.0.0 /10 4194302
1111.1111 111 255.224.0.0 /11 2097150
1111.1111 1111. 255.240.0.0 /12 1048574
1111.1111 1111.1 255.248.0.0 /13 524286
1111.1111 1111.11 255.252.0.0 /14 262142
1111.1111 1111.111 255.254.0.0 /15 131070
CLASS B
1111.1111 1111.1111 255.255.0.0 /16 65534
1111.1111 1111.1111 1 255.255.128.0 /17 32766
1111.1111 1111.1111 11 255.255.192.0 /18 16382
1111.1111 1111.1111 111 255.255.224.0 /19 8190
1111.1111 1111.1111 1111 255.255.240.0 /20 4094
1111.1111 1111.1111 1111.1 255.255.248.0 /21 2046
1111.1111 1111.1111 1111.11 255.255.252.0 /22 1022
1111.1111 1111.1111 1111.111 255.255.254.0 /23 510
CLASS C
1111.1111 1111.1111 1111.1111 255.255.255.0 /24 254
1111.1111 1111.1111 1111.1111 1 255.255.255.128 /25 126
1111.1111 1111.1111 1111.1111 11 255.255.255.192 /26 62
1111.1111 1111.1111 1111.1111 111 255.255.255.224 /27 30
1111.1111 1111.1111 1111.1111 1111 255.255.255.240 /28 14
1111.1111 1111.1111 1111.1111 1111.1 255.255.255.248 /29 6
1111.1111 1111.1111 1111.1111 1111.11 255.255.255.252 /30 2
1111.1111 1111.1111 1111.1111 1111.111 255.255.255.254 /31 0
1111.1111 1111.1111 1111.1111 1111.1111 255.255.255.255 /32 0
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