Two CCNA-related questions - subnets number and 3750 for practical

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Two questions related to CCNA:

1. Todd Lammle's book keeps talking about the number of subnets being
2^[nb.of net bits], while all other works point to a different formula:
(2^[nb.of net bits]-2). Who is right?!?

2. I have borrowed a 3750 from a friend, for a few weeks, in an attempt to
use it alongside two 2514s I've purchased from eBay, for a three-router
environment, for CCNA lab practice. The problem is that the 3750 has some
different configuration options (port in L2 or L3, for example, etc.),
that I wonder if it would have an impact on me learning the wrong way of
doing things, compared to Cisco's requirements for CCNA. So - is a 3750
advisable to be used, or should I just forget about it?

TIA,
Papi


Re: Two CCNA-related questions - subnets number and 3750 for practical



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Hi Papi

Todd and the other books are both correct.  It depends if subnet-zero is
enabled or not.  In the new CCNA exam I have heard subnet zero can be used
to match the default in the IOS ver 12. older IOS and CCNA exams used NO
SUBNET-ZERO.  With no subnet-zero the first and last subnet could not be
used hence the -2. I would check if subnet-zero is assumed in the exam
though as I took my CCNA 2 years ago.

As for the 3750 it is a L2/L3 switch and not a standard router so if the
commands confuse then just use it as a switch only. I have no experience of
the 3750 so don't know if it's IOS or CatOS so can't advise further.

Regards

Toby




Re: Two CCNA-related questions - subnets number and 3750 for practical


There you go -- good explanation of what -2 is all about...

toby wrote:
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Re: Two CCNA-related questions - subnets number and 3750 for practical


On Thu, 02 Jun 2005 17:42:22 +0000, toby wrote:
 
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Thx, Toby (and all others), for the reply. Only after having seen your
reply(ies) have I realized that this is not what I meant to ask: I knew
both were correct, under ceratin conditions, based on the inclusion (or
not) of subnet zero. What I should have asked should have been: as both
parties make their statements sound definitive, what is the assumption
under which - in lieu of specifics - one should answer such a question on
a CCNA test? Or - differently put - are the CCNA tests now specific enough
to allow one to respond correctly, by either spelling out the conditions,
or providing an IOS version? Or - even more so - is there a default
assumed (now this is hard to answer, as it relates to the IOS version - so
probably even this question should have been formulated: if any specifics
are missing, is there a default IOS assumed, that - in turn - would allow
one to know that ip subnet-zero is "prebuilt" in the configuration, or not?!?).

Thx again - sorry for the confusion,
papi



Re: Two CCNA-related questions - subnets number and 3750 for practical


hi,

I remember having the same concerns before taking the CCNA. As I remember it
there were no amiguities on the test. You understand the concepts so don't
worry about it, they're not out to trick you and if they do ask you then
they won't put both options in the answer.




Re: Two CCNA-related questions - subnets number and 3750 for practical


Answer to question 1:
The "-2" refers to the two "unusable" subnets.

I'll let someone else answer question 2.

papi wrote:
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