Yikes !!!
>For CCNA 2.0 exam x^2 -1 is the correct answer.
So, you're saying that subnet -1 (all ones) is assumed to be allowed
(which is true for Cisco routers), and subnet 0 is *not*, in the absence
an explicit "ip subnet-zero".
That's worse than I thought (or better, since it's correct ;>) !!!
-------------------------------------------------
Tks | <mailto:[EMAIL PROTECTED]>
BV | <mailto:[EMAIL PROTECTED]>
Sr. Technical Consultant, SBM, A Gates/Arrow Co.
Vox 770-623-3430 11455 Lakefield Dr.
Fax 770-623-3429 Duluth, GA 30097-1511
=================================================
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Gopinath Pulyankote
Sent: Tuesday, January 23, 2001 6:01 PM
To: [EMAIL PROTECTED]
Subject: Re: CCNA 2 and subnets
For CCNA 2.0 exam x^2 -1 is the correct answer. I did get a question on
the
similar lines & I answered it based on this, it must be correct since I
got
a 100% for that topic.
""Bob Vance"" <[EMAIL PROTECTED]> wrote in message
002d01c08573$2af4e680$[EMAIL PROTECTED]">news:002d01c08573$2af4e680$[EMAIL PROTECTED]...
> Thanks.
> I think that I pretty well understand the technical aspects.
> I know that I can use subnet -1 and subnet 0 in a Cisco environment
> (with "ip subnet-zero").
>
> My question was of a practical nature:
>
> Does the CCNA 2.0 certification test assume that we can use 0
and -1
> or does it assume that we cannot.
>
> E.g., if encountered on the CCNA 2.0 cert test, what is the answer to
> the following question:
>
> Given the Class C network, 192.168.1.0, what mask is needed to
> provide for 7 subnets?
>
> The "real" answer (in the sense of what could be configured on the
Cisco
> routers and irrespective of any restrictions that hosts on those
subnets
> might have) would be 255.255.255.224, even without "ip subnet-zero".
>
> The CCNA 1.0 answer would have been
>
> 255.255.255.240
>
> What is the answer expected by CCNA 2.0 ? (Or maybe they scrupulously
> avoid those particular questions :)
>
> And, as I said, the ICND book still subtracts 2.
>
> -------------------------------------------------
> Tks | <mailto:[EMAIL PROTECTED]>
> BV | <mailto:[EMAIL PROTECTED]>
> Sr. Technical Consultant, SBM, A Gates/Arrow Co.
> Vox 770-623-3430 11455 Lakefield Dr.
> Fax 770-623-3429 Duluth, GA 30097-1511
> =================================================
>
>
>
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
> Brian Lodwick
> Sent: Tuesday, January 23, 2001 1:17 PM
> To: [EMAIL PROTECTED]; [EMAIL PROTECTED]
> Subject: RE: CCNA 2 and subnets
>
>
> Bob,
> Howard answered this question for me a while back so I'll try to
> answer it
> for you now. This question is probobaly more in depth than you
realize,
> but
> the question comes down to why did they used to say the equation for
> finding
> the amount of valid subnets is 2^#of hosts -2? And why now do we
not -2?
> Well the short answer is -we used to use Classfull addressing. With
> classfull the reason we used the -2 was because it was a bad idea to
use
> the
> all 0's or all 1's subnets(highly discouraged is I believe the
> terminology)When an all 0's subnet update was sent to a classfull
router
> it
> would not be able to decipher it from the entire network. This is
> because in
> clasfull the masks aren't sent with the updates therefore when the
> classfull
> mask is placed on say 192.168.0.0/28 it would change it to /24 because
> again
> the mask wasn't sent. Which would end up causing some issues
obviously.
> The
> other one was the all 1's subnets. I'll just make an example. If you
> think
> along the same lines as the all 0's. Again in a classfull environment
a
> broadcast for a particular subnet would be interpreted as a broadcast
> for
> the entire network. 192.168.0.255/28 has different meaning than
> 192.168.0.255/24.
> 3Coms website has the best explaination I have found The article is
> called:
> Understanding IP addressing: Everything You Ever Wanted To Know by
Chuck
> Semeria.
> Cisco, Microsoft, and the RFC's seem to dance around the topic.
>
> >>>Brian
>
>
> >From: "Bob Vance" <[EMAIL PROTECTED]>
> >Reply-To: "Bob Vance" <[EMAIL PROTECTED]>
> >To: "CISCO_GroupStudy List \(E-mail\)" <[EMAIL PROTECTED]>
> >Subject: RE: CCNA 2 and subnets
> >Date: Tue, 23 Jan 2001 08:24:37 -0500
> >
> >Yarrggh!
> >Of course, that's
> >
> > (2^n) (*not* 2^(n-1) )
> >
> >Maybe there *is* something to that aspartame story ;>)
> >
> >-------------------------------------------------
> >Tks | <mailto:[EMAIL PROTECTED]>
> >BV | <mailto:[EMAIL PROTECTED]>
> >Sr. Technical Consultant, SBM, A Gates/Arrow Co.
> >Vox 770-623-3430 11455 Lakefield Dr.
> >Fax 770-623-3429 Duluth, GA 30097-1511
> >=================================================
> >
> >
> >
> >
> >
> >-----Original Message-----
> >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf
Of
> >Bob Vance
> >Sent: Monday, January 22, 2001 10:35 PM
> >To: CISCO_GroupStudy List (E-mail)
> >Subject: CCNA 2 and subnets
> >
> >
> >Sorry for the lame question, but I gotta know :|
> >
> >We know that subnet -1 (all ones) is valid to config in IOS and that
0
> >is OK with
> >
> > ip subnet-zero.
> >
> >For purposes of CCNA 2, do we assume that subnet 0 and -1 are valid,
> >vs. CCNA 1 (where they were not) for questions like,
> > "How many subnets can we have with this mask?
> > "
> >?
> >Does the test make it clear in preliminary text?
> >
> >The archives seem to have conflicting answers.
> >
> >The Cisco Press ICND book (McQuerry, 1-57870-111-2) doesn't address
the
> >issue head on, but simply shows tables with (2^(n-1))-2 subnets.
> >
> >The Cisco Press 640-507 Cert Guide (Odom, 0-7357-0971-8) clearly says
> >that 2^(n-1) is correct and yet points out that 0 is only valid with
> >"ip subnet-zero" !
> >
> >Does anyone know the *definitive* answer for CCNA 2.0 ?
> >
> >
> >-------------------------------------------------
> >Tks | <mailto:[EMAIL PROTECTED]>
> >BV | <mailto:[EMAIL PROTECTED]>
> >Sr. Technical Consultant, SBM, A Gates/Arrow Co.
> >Vox 770-623-3430 11455 Lakefield Dr.
> >Fax 770-623-3429 Duluth, GA 30097-1511
> >=================================================
> >
> >_________________________________
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