>
> > Ok, I looked into the resources that you've referred to, and put a little
> > more thought into this question.
Make sure the resources cover supernetting and not just subnetting. The
goal of supernetting is to group routes together so that a router reduces
the number of routes it tells other routers about. That's very different
from subnetting where the goal is to subdivide the network number assigned
to you by your ISP or ARIN.
> > So, we're given the networks,
> >
> > 192.168.9.0 (192.168.0000 1001.0000 0000)
> > 192.168.10.0 (192.168.0000 1010.0000 0000)
> > 192.168.11.0 (192.168.0000 1011.0000 0000) and
> > 192.168.12.0 (192.168.0000 1100.0000 0000).
The question was, "When using classless supernetting, which route best
summarizes the following networks?"
So we're looking for one route that will let us tell all other routers
about our four networks. The possible answers were:
A) 192.168.0.9 / 20 obviously wrong because of the .9 at the end
B) 192.168.0.0 / 16 this could work, but it's less specific than answer D
C) 192.168.9.0 / 22 this doesn't work because it leaves out
192.168.12.0, plus it would be stupid to use .9 when the one bit isn't even
referred to with a /22. The one bit is in the node ID (suffix) part of the
addresses.
D) 192.168.8.0 / 21 this works
> >
> > Keeping in mind that the question asks for the "best" summarization...
>since
> > 192.168.8.0/21 would include additional networks not mentioned in the
> > problem (i.e. 192.168.13.0, 192.168.14.0, etc.), I can see how this might
> > not be the best answer.
With a /21, the one bit and two bit don't matter so 13 and 14 don't matter.
Those bits are in the node part when we use /21.
> >
> > 192.168.9.0/22, on the other hand, is the "best" summarization for the
>first
> > three networks. The last network has no other networks to be summarized
> > with, therefore can be left out of the summarization.
The goal is to group all four networks. Leaving out one would cause you not
to meet that goal. I think D is the right answer.
Priscilla
> >
> > Is this the right reasoning for the correct answer being C?
> >
> >
> >
> > Regards,
> >
> > Han-Song Kim
> > Network Engineer, CCNP/ MCSE/ MCDBA
> > Planetary Networks
> > (W)408.745.3065 (C)408.910.7907
> > [EMAIL PROTECTED]
> >
> >
> >
> >
> > -----Original Message-----
> > From: Groupstudy [mailto:[EMAIL PROTECTED]]
> > Sent: Saturday, February 03, 2001 11:51 PM
> > To: [EMAIL PROTECTED]
> > Subject: Re: Subnet questions
> >
> >
> > I don't want to explain, it will take me too long. There have been a
>number
> > of threads regarding subnet addressing lately and they had some good
> > examples to examine. Search the archives.
> >
> > Be patient, learning to subnet and summarize off the top of your head
> > requires some time and practice. The best way to learn is to just sit
>down
> > and play with binary.
> >
> > Take a look at the following URL's for complete discussions on this topic.
> > I think you will get what you need from them:
> >
> > http://www.cisco.com/univercd/cc/td/doc/cisintwk/idg4/nd20a.htm
> >
> > http://www.3com.com/nsc/501302.html
> >
> >
> > ----- Original Message -----
> > From: Han-Song Kim <[EMAIL PROTECTED]>
> > To: 'Groupstudy' <[EMAIL PROTECTED]>
> > Sent: Saturday, February 03, 2001 8:10 PM
> > Subject: RE: Subnet questions
> >
> >
> > > Sorry about the previous response. I thought you're responding back to
>my
> > > earlier e-mail. Still, why is the answer to Q3 C, not D?
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: Groupstudy [mailto:[EMAIL PROTECTED]]
> > > Sent: Saturday, February 03, 2001 7:31 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: Re: Subnet questions
> > >
> > >
> > > B is the correct answer.
> > >
> > > ----- Original Message -----
> > > From: Andy <[EMAIL PROTECTED]>
> > > To: Hunt Lee <[EMAIL PROTECTED]>
> > > Cc: <[EMAIL PROTECTED]>
> > > Sent: Saturday, February 03, 2001 9:40 AM
> > > Subject: Re: Subnet questions
> > >
> > >
> > > >
> > > >
> > > > On Sun, 4 Feb 2001, Hunt Lee wrote:
> > > >
> > > > > I have three subnet / route summarization questions but I don't
> > > > > understand the answer, any help would be greatly appreciated.
> > > > >
> > > > > Q1) Choose the appropriate classless network address and broadcast
> > > > > address for the IP address 10.6.38.50 with a subnet mask of
> > > > > 255.255.240.0
> > > > >
> > > > > A) 10.6.38.49 and 10.6.38.62
> > > > >
> > > > > B) 10.6.32.0 and 10.6.47.255
> > > > >
> > > > > C) 10.6.38.0 and 10.6.38.255
> > > > >
> > > > > D) 10.0.0.0 and 10.255.255.255
> > > > >
> > > > > Answer is B.
> > > >
> > > > No its not. The answer is 10.6.38.48 and 10.6.38.63. It probably meant
> > to
> > > > say classful.
> > > >
> > > > > Q2) Given a classless route summarization of 72.8.0.0 /13. Which IP
> > > > > address fall into this scope?
> > > > >
> > > > > A) 72.15.36.8
> > > > >
> > > > > B) 72.13.1.1
> > > > >
> > > > > C) 72.8.20.10
> > > > >
> > > > > D) 72.7.200.100
> > > > >
> > > > > E) 72.16.7.4
> > > > >
> > > > > F) 72.40.1.8
> > > > >
> > > > > Answer is A, B & C - why isn't E the ansewr as well?
> > > >
> > > > The range of 72.8.0.0/13 is 72.8.0.0 - 72.15.255.255. Its 8 Class B's.
> > > >
> > > > > Q3) When using classless supernetting, which route best summarizes
> > > > > the following networks?
> > > > >
> > > > > 192.168.9.0
> > > > > 192.168.10.0
> > > > > 192.168.11.0
> > > > > 192.168.12.0
> > > > >
> > > > > A) 192.168.0.9 / 20
> > > > >
> > > > > B) 192.168.0.0 / 16
> > > > >
> > > > > C) 192.168.9.0 / 22
> > > > >
> > > > > D) 192.168.8.0 / 21
> > > > >
> > > > > I thought D is the answer, but the answer is C.
> > > >
> > > > A /22 is 4 Class C's, a /21 is 8. I recommand finding or making (to
> > > > actually learn it) a subnet table and just keeping referencing it
>until
> > > > you don't need to anymore.
> > > >
> > > > andy
> > > >
> > > > _________________________________
> > > > FAQ, list archives, and subscription info:
> > > http://www.groupstudy.com/list/cisco.html
> > > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
> > > >
> > >
> > > _________________________________
> > > FAQ, list archives, and subscription info:
> > > http://www.groupstudy.com/list/cisco.html
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> > >
> >
> > _________________________________
> > FAQ, list archives, and subscription info:
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> >
>
>_________________________________
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________________________
Priscilla Oppenheimer
http://www.priscilla.com
_________________________________
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