Classful-classless

Hi-can anyone tell me if my understanding of this is correct? if a subnet is unknown in a network using classful addressing scheme-the packet is discarded- whereas with classless the packet is forwarded,regardless of whether it is a known subnet? All cisco routers are default classless? thanks alot

Reply to
greg johnstone
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Yes

No, the packet will still be dropped, unless a default route is configured on the router; in which case the packet will be forwarded out on that route.

Well, this is configurable in any event.

Aubrey

Reply to
Aubrey Adams

Thanks Aubrey, do you know if there are many questions on this in the CCNA exam? Cheers

Reply to
greg johnstone

You can be sure that there will be questions on classless and non-classless (classful) addressing and routing, and on default routing in the CCNA exam.

However, the number and context will vary. And well I'm reasonably sure that a question asking for a "definition" of classful/classless router operation proabably will not be asked, there will be than one question covering the areas of troubleshooting and router configuration.

This means you need to know how to *apply* this knowledge in particular circumstances.

EG Determine the fixed or variable mask to optimise a given addressing scenario. Configure interfaces to implement a given addressing scenario Configure routing protocols to implement a given classless or classful addressing scenario Configure static and default routing to implement a given classless or classful addressing scenario Given the output from particular show or debug commands troubleshoot and correct a given classless or classful addressing scenario

cheers Aubrey

Reply to
Aubrey Adams

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