Indeed some people make it a habit of specifying the inverse mask of the
subnet-mask of the interface they want to enable OSPF on. As Bryan said,
there is absolutely no reason for doing that, unless a task only allows you
to use one or a specific number of network statements.
Both in the CCIE lab and in real life you want to be as specific as
possible, so by using a 0.0.0.0 inverse mask you only match on the given IP
address and you will never run into strange things. Saves another
frustration during your exam :-)

--

Regards,

Rick Mur
CCIE2 #21946 (R&S / Service Provider)
Sr. Support Engineer – IPexpert, Inc.
URL: http://www.IPexpert.com


On Tue, Sep 1, 2009 at 4:33 AM, Bryan Bartik <[email protected]> wrote:

> Hello Uli,
>
> The only reason I can think of not to use 0.0.0.0 is when you want to cover
> more the one interface with the network statement. It certainly does not
> need to match the subnet mask and there is no functional difference if it
> does or not.
>
> -hth
>
>
> On Mon, Aug 31, 2009 at 7:13 PM, Stan <[email protected]> wrote:
>
>>  They are both valid and it all depends on how specific you need to be in
>> enabling OSPF. Ipexpert workbooks will walk you trough, just keep
>> reading..:)
>>
>> Stan
>>
>>
>>
>> On 8/31/09 6:10 PM, "Uli" <[email protected]> wrote:
>>
>> Hi guys,
>>
>> When I studied CCNP in CNAP we configure ospf wildcard masks just using
>> the reverse of netmask. However, in CCIE we need to be more specific so we
>> use 0.0.0.0 for wildcard masks. Does anyone know what the difference between
>> them and which one is more prefer in exam lab ?
>>
>> Cheers :)
>>
>> ------------------------------
>> _______________________________________________
>> For more information regarding industry leading CCIE Lab training, please
>> visit www.ipexpert.com
>>
>>
>> _______________________________________________
>> For more information regarding industry leading CCIE Lab training, please
>> visit www.ipexpert.com
>>
>>
>
>
> --
> Bryan Bartik
> CCIE #23707 (R&S), CCNP
> Sr. Support Engineer - IPexpert, Inc.
> URL: http://www.IPexpert.com
>
> _______________________________________________
> For more information regarding industry leading CCIE Lab training, please
> visit www.ipexpert.com
>
>
_______________________________________________
For more information regarding industry leading CCIE Lab training, please visit 
www.ipexpert.com

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