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IP Binary Converter
Convert between dotted-decimal and binary notation — with octet-by-octet breakdown
Examples:
11000000.10101000.00000001.00000001
Octet breakdown
192
11000000
168
10101000
1
00000001
1
00000001
Octet 1Octet 2Octet 3Octet 4
Common decimal ↔ binary values
25511111111
25411111110
25211111100
24811111000
24011110000
22411100000
19211000000
12810000000
000000000
100000001
12701111111
16810101000
Why binary matters for subnetting
Subnetting is fundamentally a binary operation. The subnet mask is a sequence of 1s (network bits) followed by 0s (host bits). When you AND an IP address with a subnet mask in binary, the result is the network address. Understanding the binary representation of common values (128, 192, 224, 240, 248, 252, 254, 255) lets you work out subnet calculations mentally — a skill that saves significant time on the CCNA exam.
The 8 subnet mask values you must memorise
128=10000000(128)
192=11000000(64)
224=11100000(32)
240=11110000(16)
248=11111000(8)
252=11111100(4)
254=11111110(2)
255=11111111(1)