subnet mask

hi everyone
i was jus wonderin why isit that with a subnet mask of
255.255.255.0 we can have one subnet and 254 hosts?
i noe why 254 hosts...coz 2^8-2=254
but why one subnet?
thanx a million in advance:)

I'm not sure what you are asking here. But 255.255.255.0 is not subnetted, unless your address happens to start with anything less that 192, then you have a subnetted address.

If not, you have a class C address and no subnet. If you subnet this address, you will not have 254 hosts any more. Each subnect "split" will lose you addresses, as each subnet will need to drop 2 addresses for network and broadcast.

Hope this helps,

Tom.

Hey indibluez

with a mask of 255.255.255.0 ( default C class ), u havent subnetted ur network as yet , so u do have 254 hosts , but only 1 network and no subnets.

The previous posts have pretty much covered this question!

You might want to read the subnetting section once again indebluez, especially if your new to the subnetting concept. Reading the material again and again will help you slowly understand how it works.

Considering the 'subnetting' topic is classified difficult for people that are new to it, I'd give it some time to let it sink in.

Cheers,

its actually from the celticrover site....one of the ACCESS LIST LABS-telnet

the router has a serial and an ethernet interface, and we are supposed to block telnet access into the router...
the serial interface is connected to the rest of the network...
the ethernet int is connected to the host

the ans given -the router was configured such that theres an access list placed at both the interfaces denying access to the router.

I don;t understand why there should be an access-grp at interface serial with an "in"

interface serial 1
ip access-group 100 in
interface ethernet 0
ip access-group 100 in

shouldn't it be out?and cant we place both access-list on the same interface?why differnt int..

Thanx alot again

sorry when i posted it kept saying error...