In Binary Net Masking each Octet contains exponential bits from right to left: 1     1   1   1   1 1 1 1 128 64 32 16 8 4 2 1 (128+64+32+16+8+4+2+1=255) So.. 255.255.248.0 in binary is 11111111. 11111111. 11111000. 00000000 = /21 (we’ll get to the identifier in a minute) 255-248 = 7 Therefore 255.255.248.0 – … Continue reading Classless networks are in style. It’s just basic subnetting.