x5150 wrote: Theres a question in my Sybex cd that came with the Lammle book that doesn't make sense to me. The question reads. Which of the following IP's fall into the CIDR block of 110.68.4.0/18? (Choose three). a) 110.68.8.32 b) 110.68.7.64 c) 110.67.6.255 d) 110.66.3.254 e) 110.65.5.128 f) 110.64.12.128 This is how i am trying to solve the question. Class A address Mask /18 255.255.192.0 So 2nd octet, we have block size of 1 third octet, size 64 Therefore my choices would only be a and b, they are the only ones even in the 110.68 subnet But the answers are b,c,e. The cd says... A class A network address with a /18 is 255.255.192.0 The subnets in the third octet are 0,64,128,192. The network address in question is 110.64.0.0, with a broadcast of 110.64.127.255, since the next subnet is 110.64.128.0
