what is meant by subnet and subnetmask?give example?

Answer 1

Subnetting an IP network allows a single large network to be broken down into what appear (logically) to be several smaller ones. It was originally introduced before the introduction of classful network numbers in IPv4, to allow a single site to have a number of local area networks.

A network mask, also known as a subnet mask, netmask or address mask, is a bitmask used to tell how many bits in an octet(s) identify the subnetwork, and how many bits provide room for host addresses.

An example :

For the IP Address 129.158.241.56, the subnet is 129.158.241 and the network mask is ffffff00.

Answer 2

Think of an IP address as being like a phone number (555-444-3333). The phone number will have area code (555), exchange (444) and the actual phone (3333).

On a network, all computers on the same subnet will have IP address that begin with the same numbers. Such as if you have a home network, all your computer normally begin with 192.168.0.xxx. Each number (xxx) can only be between 0 and 255. So a computer network could have, at most, 256 devices on it.

If you need 500 computers, you would have to create additional subnets within your network, such as 192.168.1.xxx. You would continue to add subnets (192.168.2.xxx, 192.168.3.xxx) as you need more computers. All these subnets are hooked together by a router to make one large "Class C" network.

Some network need to be large enough to hold more then 256 computers on a single subnet. So there is another way of addressing the computers. You use the first two numbers only, 192.168.xxx.xxx, as the subnet address, and the last two numbers for the individual PCs (xxx.xxx). This lets you put 256x256 (65,536) computers into one gigantic single subnet. This is known as a "Class B" network.

But now you have a problem. Both a Class B and a Class C network can have a PC that is number 192.168.100.100. The network needs a way to know how much of the number is the subnet and much is the PC. That is the job of the subnet mask.

If the subnet mask is set to 255.255.255.0, that tells the network to only use the last number (whatever is "0") as the PC address. 255.255.255.0 would be a Class C network. 255.255.0.0 would be a Class B network. (Can you guess what 255.0.0.0 would be? Yes, a Class A network with only the first number as the subnet and the other three as the invidual PCs).

Answer 3

The word subnetwork (usually shortened to subnet) has two related meanings. In the older and more general meaning, it meant one physical network of an internetwork. In the Internet Protocol (IP), a subnetwork is a division of a classful network. The rest of this article is about the second meaning.

Subnetting an IP network allows a single large network to be broken down into what appear (logically) to be several smaller ones. It was originally introduced before the introduction of classful network numbers in IPv4, to allow a single site to have a number of local area networks. Even after the introduction of classful network numbers, subnetting continued to be useful, as it reduced the number of entries in the Internet-wide routing table (by hiding information about all the individual subnets inside a site). As a side benefit, it also resulted in reduced network overhead, by dividing the parts which receive IP broadcasts.

View the source page for more information with Example

Answer 4

Using dial up is good example...when u go to set up connection for dial-up usually just check automatic in finding IP...but if that does not work ....some times u have to go in and set ur sub net physically in ur tcp/ip in ur internet protocol

Answer 5

see this site http://www.learntosubnet.com