642-642 Cert Study Question

[Adil Nasser]

Hello All,

I need feedback from the forum as to what should be the correct answer to this practice question found in the book:
"IP Telephony Self-Study Cisco QoS Exam Certification Guide, Second Edition by Wendell Odom/ Michael J Cavanaugh"

The question is:

what fragment size, in bytes, should be used on a 256-Kbps link in order to ensure each fragment has less than or equal to 10 ms of serialization delay?

a. 80
b. 160
c. 214
d. 240
e. 320
f. 480

The book is stating that the correct answer is D. but when I use the formula:
fragment-size * 8/linkspeed = serialization delay
I come up with the answer of E. (320).
Can you someone help me understand which answer is correct and why?


Thanks in advance for your help.
Adil Nasser

[Scott Morris]

Should be E. 80 bytes per 64k of link speed.


HTH,
Scott

[Adil Nasser]

While the book is stating that the correct answer is D, it also is tating that 320 is the correct answer. I just noticed this after posting my question. So Scott, you are indeed correct. Thanks for your feedback.


Adil

[Scott Morris]

No worries... I actually just sat the QoS exam this morning.... Very strange little exam. There's a few things I need to go lab up now, because I'm pretty sure a few of the scenarios had zero right answers. Yay.


Scott