Prep exam explanation

Unanswered Question
Jun 26th, 2007

Exam 3 Question 11

This question asks to choose which address to use for the most efficient serial addressing scheme. Why is choice F correct as opposed to D or E?

I have this problem too.
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benson9010 Tue, 06/26/2007 - 08:53

Here is the gist of the question -

From the cisco prep practice exams a question says use the most efficient addressing scheme and vlsm to configure a serial connection between two routers, which address can be configured on one of the serial interfaces?

A) 192.168.16.63/27

B) 192.168.16.158/27

C) 192.168.16.192/27

D) 192.168.16.113/30

E) 192.168.16.145/30

F) 192.168.16.193/30

They say F is correct, why wouldn't D and E be correct as well?

royalblues Tue, 06/26/2007 - 11:43

I think there must be a typo either in the SM or the ip address

Narayan

rwjackson59 Tue, 06/26/2007 - 18:10

Because the IP addresses 192.168.16.113/30 and 192.168.16.145/30 have already been allocated. Looking at the graphic, 192.168.16.113 is within the IP range of the 192.168.16.96/27 subnet, and 192.168.16.145 is within the IP range fo the 192.168.16.128/27 subnet. So the only /30 subnet choice that is not already allocated is F) 192.168.16.193/30.

Randy

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royalblues Tue, 06/26/2007 - 20:45

Did i miss the graph attached.. i did not see one :-)

If that is the case then randy is right. If the subnets mentioned are already a part or fall within other subnet, only the valid subnet that is remaining can be used

Narayan

rwjackson59 Wed, 06/27/2007 - 04:25

The graphic is in group 3, question 11 of the practice questions in the CCNA Prep Center. I didn't think I should attach it because it is Cisco intellectual property. Sorry :-(

I recognized the scenario because I used those practice questions repeatedly when preparing for the CCNA test. I passed Monday!

Randy

royalblues Wed, 06/27/2007 - 04:51

In that case you are absolutely correct and the correct answer would be " F"

And congratulations on passing the exam

Narayan

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