Zero Subnet needs explaining to me?

Morning,

is it just me or does everyone quite frequently come across some topics and think "what the f are you on about"?

Can someone please explain this topic to me? I've searched for this and still cant grasped the fundementals of Zero Subnet.

Maybe someone on this quality forum can provide a simple explanation for Zero subnet and allow me to move on with my studying.

thanks

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Comments

jibbajabba

Are you talking about the ip subnet-zero command ?

It allows you to start at block zero in terms of available IP addresses (I think).

When a /24 gives you 256 addresses for example, subnet-zero means you can start at 0 (0-255) rather than 256 ...

I hope that makes sense (and is correct to begin with) - I am no Cisco monkey and I just remember a phone conversation I over-heard once ..

atorven

It's the very first subnet after subnetting(hope that makes sense) Take a look at the example below;
192.168.0.0/24 <== subnet zero
192.168.1.0/24
192.168.2.0/24

It will all become clear once you learn to subnet.

DANMOH009

A quick way of me remembering is, If IP subnet zero is not configured, then we cant start at zero when counting the subnets involved.

Beany

DANMOH009 wrote: »

A quick way of me remembering is, If IP subnet zero is not configured, then we cant start at zero when counting the subnets involved.

So the command 'no ip subnet zero' is used when subnet zero is not configured/used?

Beany

atorven wrote: »

It's the very first subnet after subnetting(hope that makes sense) Take a look at the example below;
192.168.0.0/24 <== subnet zero
192.168.1.0/24
192.168.2.0/24

It will all become clear once you learn to subnet.

cool... so does the cisco devices by default allow us to use the subnet zero or do we have to manually configure the router?

atorven

Yes, by default most routers now days should have ip subnet zero turned on. If you don't want to use zero subnets then you turn it off by by issuing the no ip subnet zero command, from my studies so far I can't see what benefit you would gain by turning it off.

FloOz

I posted a very similiar question regarding subnet zero last week. here is the thread.
http://www.techexams.net/forums/ccna-ccent/82174-subnet-zero-help.html

Beany

FloOz wrote: »

I posted a very similiar question regarding subnet zero last week. here is the thread.
http://www.techexams.net/forums/ccna-ccent/82174-subnet-zero-help.html

Thanks for this