preparation question from book seems wrong: confirmation?

Hi all,

I am studying for doing my CCNA exam.
In the book of Lammle Todd I got the following question:
9. What are two purposes for segmentation with a bridge?
A. To add more broadcast domains
B. To create more collision domains
C. To add more bandwidth for users
D. To allow more broadcasts for users

To me this should be b and c. However the answer mentioned is a and d. This seems really strange to me. So I guess it is wrong. And if it isn't wrong, can someone explain to me why these are correct? Or do I misinterpret this question?

NOTE: I think for the rest this book is rather good. But as soon as I find a mistake in some answer I really start doubting if I am learning something wrong or not and if I will actually pass the exam

really annoying

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Comments

ptilsen

The book is wrong. Since bridges separate collision domains, a bridge actually creates collision domains. Each connection is its own collision domain. Thus, B is correct. Since a bridge does not separate or create broadcast domains, A is incorrect. Since a bridge can provide full-duplex, collision-free connections, that is in a sense adding bandwidth, so I would choose C. A bridge does not directly impact the ability to create broadcasts, so I'm don't see how D could be correct.

Are you sure the question wasn't "Which of the following are not purposes for segmentation with a bridge?"

thedude666

I did a copy paste of the question

it could be that "not" is accidentally left out and in that case the answers indeed seem correct.

Thanks for confirming my initial thoughts. One thing I am doubting if you actually get more bandwidth. I would think not, but that it is used more efficiently. However b and c seem the only logical correct answers in the end

Todd Burrell

Check the errata for the book. I seem to remember this question was wrong. Look on www.lammle.com and you can find the error data for the book.

You are correct that this question as asked should have B and C as the answers.

ptilsen

Just for comparison, I submitted 12 emails to Transcender for incorrect questions/answers/categorization on their 70-643 practice questions. I submitted about six to Preplogic for their Security+ exam. I've found more minor errors in MS Press books.

No one's perfect, and almost any study source is going to have problems. Never be afraid to ask if your material is wrong when it seems wrong. If you're wrong, you'll gain a stronger understanding of the material in learning why you're wrong. If the material is wrong, your actions may result in its correct by the vendor providing it or lead you to other corrections.

ptilsen

thedude666 wrote: »

Thanks for confirming my initial thoughts. One thing I am doubting if you actually get more bandwidth. I would think not, but that it is used more efficiently.

Well, I can't say how Cisco defines it. You will get better data rates, but I don't know that that's considered "more bandwidth". Certainly, the purpose is accurately described as "making a faster network".

sizeon

You get more bandwidth by running in Full duplex mode. Also, there each port is its own collision domain

ptilsen

sizeon wrote: »

You get more bandwidth by running in Full duplex mode. Also, there each port is its own collision domain

Technically your bandwidth is still the same unidirectionally, give the scenario of a 10mbps hub and a 10mbps bridge. The fact that it is full-duplex simply makes that bandwidth two-way and collision free, thus resulting in better throughput in most scenarios.

It's just an issue of how you define bandwidth. The vernacular use in computing generally refers to throughput as a data rate (bits/time) value. The definition in signaling is very different. Unfortunately, which definition is in use is highly relevant when it comes to networking and equipment, and I can't say one way or another how Cisco defines it or uses it on exams.

thedude666

ptilsen wrote: »

Technically your bandwidth is still the same unidirectionally, give the scenario of a 10mbps hub and a 10mbps bridge. The fact that it is full-duplex simply makes that bandwidth two-way and collision free, thus resulting in better throughput in most scenarios.

That was indeed what I expected. So that made me even doubt about C as a correct answer.

Just for comparison, I submitted 12 emails to Transcender for incorrect questions/answers/categorization on their 70-643 practice questions. I submitted about six to Preplogic for their Security+ exam. I've found more minor errors in MS Press books.

No one's perfect, and almost any study source is going to have problems. Never be afraid to ask if your material is wrong when it seems wrong. If you're wrong, and you'll gain a stronger understanding of the material in learning why you're wrong. If the material is wrong, your actions may result in its correct by the vendor providing it or lead you to other corrections.

I checked with some folks and they told me that Cisco Press is actually pretty good and they don't know of any faults in the answers. They used Cisco Press to study for their exam. I might buy that book. First I'll check how far I get with the Tod Lammle book.

PS: I'll check the Tod Lammle site and see if I find the errata. Thanks for pointing that out!

thedude666

Found that the answer should indeed be b and c in the errata

Sybex: CCNA Cisco Certified Network Associate Study Guide: Exam 640-802, includes CD-ROM, 7th Edition