Here is our subnet reference guide and The Perl script used to generate it
If you want an easy to use subnetting calculator, Subnet-Calculator.org is one of the best ones we’ve seen online.
Subnet Reference Guide -- 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
