# subnetting Class A

Posts: 42Member ■■□□□□□□□□
Theres a question in my Sybex cd that came with the Lammle book that doesn't make sense to me.

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.
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

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

• Posts: 3Member ■□□□□□□□□□
x5150 wrote:
Theres a question in my Sybex cd that came with the Lammle book that doesn't make sense to me.

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.
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