Classful routing protocols summarize to an 8-bit boundary. The boundary
depends on the class, A, B, or C.
I read the question from the point of view of someone designing an
addressing scheme, however, not from the point of view of what a router
would send.
With classful addressing, we can place the network/subnet/host boundary
anywhere to the right of the classful barrier. The question asks about a
pretty typical case where we want 512-2 hosts and 128-2 subnets on a Class
B network. That was allowed long before classless stuff came along.
Priscilla
At 07:45 PM 7/24/01, Michael L. Williams wrote:
>I would agree...... I always believed classfull meant it *does* end on an
>8-bit boundary..... i.e. For Class A it's 255.0.0.0, for Class B it's
>255.255.0.0, and Class C it is 255.255.255.0. Given that I would also agree
>with Ed that the answer would be 172.18.255.255.
>
>But hey! What do I know......... ya think ya know something, and WHAMO,
>it's not quite as clear as one might have originally thought!
>
>Mike W.
>
>"Priscilla Oppenheimer" wrote in message
>[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > Send it to the list. Seems like a good argument to me.
> >
> > Priscilla
> >
> > At 05:48 PM 7/24/01, Guy Russell wrote:
> > >Actually I disagree...
> > >
> > >Routers using Classful addresses, do not look at the subnet mask, nor do
> > >they transmit the subnet mask...Since the term classful was used, we
>would
> > >obviously be talking about the routing protocol, so a broadcast would be
> > >based only on the first octet to decide.
> > >
> > >Now a machine is not dependent on classful, it understands its own
subnet
> > >mask, and then the answer would be that... But the term Classful negates
> > >that theory of it being a computer or other host...
> > >
> > >
> > >
> > >----- Original Message -----
> > >From: Priscilla Oppenheimer
> > >To:
> > >Sent: Tuesday, July 24, 2001 5:28 PM
> > >Subject: Re: ccna challenge question [7:13565]
> > >
> > >
> > > > At 04:28 PM 7/24/01, Ed Moss wrote:
> > > > >The key in the question is the word "classful".
> > > >
> > > > Classful doesn't mean it has to end on an 8-bit boundary.
> > > >
> > > > >This is a Class B address
> > > > >with a 16 bit classful mask.
> > > >
> > > > It's not 16-bit. It says the mask is 255.255.254.0. That's 23 bits in
>the
> > > > prefix (network) part.
> > > >
> > > > The answer is B. Put it in binary to understand it.....
> > > >
> > > > Priscilla
> > > >
> > > > >I would have to say the correct answer would
> > > > >be 'C' 172.18.255.255.
> > > > >Ed
> > > > >
> > > > > > Using classful assumptions, what is the directed broadcast
address
> > for
> > > > > > 172.18.2.0 with the mask 255.255.254.0?
> > > > > > a) 172.18.2.255
> > > > > > b) 172.18.3.255
> > > > > > c) 172.18.255.255
> > > > > > d) 172.18.0.0
> > > > >
> > > > > > Answer
> > > > > > b)
> > > > ________________________
> > > >
> > > > Priscilla Oppenheimer
> > > > http://www.priscilla.com
> > ________________________
> >
> > Priscilla Oppenheimer
> > http://www.priscilla.com
________________________
Priscilla Oppenheimer
http://www.priscilla.com
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=13677&t=13565
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