subnetting question - pissing me off

For some reason, this question has me lost - particular cidr question

Which of the following IP addresses fall into the CIDR block of

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

Book lists answers as B,C,E.

I see /18 meaning block size of size of 64. I do know this is a class A address being "110".

Some reason I am stumped on this one. Any help appreciated.

For some reason, this question has me lost - particular cidr question

Which of the following IP addresses fall into the CIDR block of

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

Book lists answers as B,C,E.

I see /18 meaning block size of size of 64. I do know this is a class A address being "110".

Some reason I am stumped on this one. Any help appreciated.

Work out what the range of ip addresses are covered by that block.

Doan

The book gave the following answers:

Answers are: B, C, E.

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 the question is 110.64.0.0, with a bcast of 110.64.127.255, since the next subnet is 110.64.128.0.

B,C,E are the correst host id's.

Can anyone work this out perhaps.

Doan wrote:

Errata for the book:

It seems this book had updated errata Doan. So the questi> The book gave the following answers:

My mistake. The third octet are being divided into blocks of 64. Thus,

Doan

Which of the following IP addresses fall into the CIDR block of

That's the updated question Doan.

Doan wrote:

Doan, notice the second Octets in the erratas updated question?

it's all .68's , meaning they fall in the .64 subnet

original question is missprint with 2nd octets varrying, 68's, 67's,

snipped-for-privacy@gmail.com wrote:

Paul's oft repeated tip. 256-mask = size of subnet.

That mask would give subnets of 110.68.0.0 and the next one would be

The mask has changed too.

And this now works out after the mask change and ip corrections.

/bad editor! bad!

Yep, 5th edition of CCNA by sybex(Tod Lammel) is full of errors

This is not good, because this book is recommended to a lot of new comers who dont want to spend the $$ on ccna wendel odom ciscopress books

Im thinking about ditching my sybex book, because this is very disconcerting when coming across errors like this.

Grog wrote:

I used the book and thought it was pretty good, providing you corrected the errors and downloaded the two extra chapters on OSPF elections and NAT.

The question you quoted at the start had me stumped too for ages, until I checked out the errata ;)