subnetting...

hi all,
i am new to networking field. i have some doubts about subnet mask. what is subnet mask ? why we are using subnet mask? what is the need to use subnet mask? Using ip address only we can identify the device in the network, then why we are using subnet mask? plz help me. i am very much confused about this topic.

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This is extremely brief, your PC (host) uses your IP and the subnet mask to distinguish IPs that belong to the same local LAN from IPs that belong to other LANs (which the packets destined for them should be forwarded to the gateway router).

More info is here: www.firewall.cx/ip-subnetting-basic-concepts.php
www.interactiveaudiovisual.com/2008newsl...ue12-SubnetMasks.pdf

Have a read on this and if you have any further questions, feel free to ask.

Thanks Solo.. This links are informative..

Thanks for sharing.

Thanks SOIo. Thanks for clarifing my doubts. Actually in our office we are using 10.2.100.1 network here we should use 255.0.0.0 as default subnet mask. it is default for class A. but in our office we are using 255.255.255.0 as subnet mask. how it is possible? if we can use any default subnet mask for any class then what is the use of subnetmask?

Sure ramachandraraju

On your 10.2.100.1 network. Using a 255.0.0.0 mask will let you have an IP range from 10.0.0.1 to 10.255.255.254. While using a 255.255.255.0 mask gives you a smaller range from 10.2.100.1 to 10.2.100.254.

thanks solo,

now i understood.
thanks for clarifying my doubt.