Subnet Reference Guide + Perl script to generate it
Here is our subnet reference guide and
The Perl script used to generate it
Subnet Reference Guide -- http://www.netadmintools.com
Value of individual bits in an eight bit byte if true:
Bit 7 = 128
Bit 6 = 64
Bit 5 = 32
Bit 4 = 16
Bit 3 = 8
Bit 2 = 4
Bit 1 = 2
Bit 0 = 1
Class 1st Octet start (binary) Decimal Range
A 0 1-126
B 10 128-191
C 110 192-223
Subnet Block Max #C IPs/ #B IPs/ #A IPs/
Mask Size Subnets Subnet Subnet Subnet
---------------------------------------------------------------------
192 64 2 62 16382 4194302
224 32 6 30 8190 2097150
240 16 14 14 4094 1048574
248 8 30 6 2046 524286
252 4 62 2 1022 262142
254 2 126 0 510 131070
255 1 254 0 254 65534
Valid Block Chart
------------------------------------------
Size 16 Size 32 Size 64
------------------------------------------
17- 30 33- 62 65-126
33- 46 65- 94 129-190
49- 62 97-126
65- 78 129-158
81- 94 161-190
97-110 193-222
113-126
129-142
145-158
161-174
177-190
193-206
209-222
225-238
Click here for text-only version.
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