Requirement is 8 networks with 30 hosts 255.255.255.0 = 11111111.11111111.11111111.00000000 8 networks = 1111 with increment of 16 which is less host number than require. 30 hosts = 11100000 with increment of 32 255.255.255.224 or 11111111.11111111.11111111.11100000 8 networks for /27 are 0,32,64,96,128,160,192,224