Default Routes and Classless Addressing

mattrgee

Hi all,

I'm reading the Cisco Press ICND2 book and found a section which is a little ambiguous:

"Classful routing places one restriction on when a router can use its default route, resulting in cases in which a router has a default route, but the router chooses to discard a packet rather than forwarding the packet based on the default route"

Page 190.

Can someone expand on this, I'm yet to find a definitive answer...

Thanks in advance.

mattrgee

Hmmm I think I got it.

With classful routing, the router will first check for a class A, B, C route in which the destination resides, if it doesn't find one it simply discards the packet without considering the default route.

Seems a bit harsh?