[c-nsp] Current CCNA tests

[Gert Doering]

Hi,

On Tue, Jan 08, 2008 at 11:36:18PM +0100, Peter Rathlev wrote:
> On Tue, 2008-01-08 at 22:51 +0100, Gert Doering wrote: 
> > Do they still ask about "Class B" networks, and "how many subnets of
> > 16 hosts can you put into a Class C" (ignoring the now-default of
> > "ip subnet-zero") and such crappy stuff?
> 
> I may be pedantic now (it' getting late!), but "ip subnet-zero" doesn't
> change the number of hosts you can cram into an unsubnetted /24
> network, class C or otherwise, does it? As I understand it, it just
> means that you can use the first subnet of a network, like the
> 10.0.0.0/24 subnet of 10.0.0.0.

The answer to "how many subnets of size 16 can you stuff into a class C"
is "15" or "16", depending on whether "ip subnet-zero" is in use...

I wasn't asking about "how many hosts" :-)

> > This is the sort of question that annoys me most - stupid historic brain
> > garbage that shouldn't be *taught* to people in the first place.
> 
> Well yeah, classful addressing is mostly historical. But ICND also
> covers RIPv1, right?
> 
> Anyway, I still find it funny that even a lot of professionals can't
> distinguish the 3.4.5.0/24 (a subnet) from 201.202.203.0/24 (a network).

There *is* *no* *difference*.

Class X networks do not exist anymore.  Networks are specified by a base 
address and a netmask / CIDR bits.  "Subnet" and "Supernet" are terms from 
the last century *that have no meaning anymore* in a CIDR environment.

(If there is a difference between 3.4.5.0/24 and 201.202.203.0/24, it's
because the *implementation* in a given router has not arrived in the
21st century, and has implicit assumptions on things based on two bits
in front of the network address.  But that's broken implementations.)

gert
-- 
USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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