-1

Possible Duplicate:
What are the essentials of a Subnet mask?

hi,

In all the machines having internet connections , i can see a value called subnet mask associated with the TCP/IP properties of the ethernet interface.

what is the logic behind it? or how can i calculate from a particular IP address?

I just read it from some blogs but it was not clear

Community
  • 1
Renjith G
  • 263
  • 1
  • 2
  • 16
  • 2
    And -1 [for ignoring this](http://img.skitch.com/20100924-cmr145qd78m2ca3rp3af1wupj6.png). (Hence, see also [ What is a subnet mask, and the difference between a subnet mask of 255.255.255.0 and 255.0.0.0?](http://superuser.com/questions/54802/what-is-a-subnet-mask-and-the-difference-between-a-subnet-mask-of-255-255-255-0)) – Arjan Sep 24 '10 at 21:35

2 Answers2

2

This is best answered by Wikipedia, see CIDR notation to understand the importance of subnet masks.

MaQleod
  • 13,149
  • 4
  • 40
  • 61
1

The subnet mask is what determines how many clients are assigned ip addresses within that domain and how many subnets can be created. That is determined by the subnet mask. A 255.255.255.0 can have 254 hosts (clients with IP addresses) on a single subnet. With two subnets there are 126 hosts. While a subnet address with 255.0.0.0 with a single subnet can yield over 16 million hosts.

There is a simple calculator here that is useful.

Since this is only a simplified answer this wiki goes into greater detail.

James Mertz
  • 26,224
  • 41
  • 111
  • 163