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Bravo020
11-17-2008, 06:50 AM
A question on Route summarization, this question is one of the Boson examples that was included with the Cisco Press Exam Certification Library, so certainly not a dump as far as I am aware.

The question presented is as follows:


An engineer has implemented manual route summarization of EIGRP in which the one summary
route is 172.16.128.0/19. Another engineer needs to install a new VLAN and subnet.
The following are some of the subnet numbers being considered by this second engineer
for the new subnet. Which one lists a subnet that would not be represented as part
of the existing summary route?

A. 172.16.144.0/28
B. 172.16.164.160/28
C. 172.16.180.0/28
D. 172.16.152.128/28
E. 172.16.124.0/28From my own understanding of the question the correct answers as far as I can tell would be B,C and E, since the summary route represents the address range 172.16.128.0 - 172.16.159.255

B and C are both definitely outside of this address range, as is E since that would only cover the range 172.16.124.0 - 182.16.124.15.

However, the answer that is provided by Boson for this question is that only B and C are correct....?

I'm assuming that this must be a mistake since I can see no reason why the summary route would include the address range 172.16.124.0 - 182.16.124.15.. .

Can anyone confirm my thought on this.

Many thanks and regards.

lildeezul
11-17-2008, 07:01 AM
yeah the summary route should only include 172.16.128.0 - 172.16.159.254, with a .255 as the broadcast

becuase a /19 is a 255.255.224.0 which means a size 32 block in the third octect. 128 + 32 = 160 ......160 - 2 = 159.254 with 159.255 being the broadcast for the subnet.

once again... you are correct.

good job !

Bravo020
11-17-2008, 07:05 AM
Thanks for the rapid reply and confirmation.

Regards.