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The purpose of a subnet mask?

By den_santiago ·
I'm wondering what's the use of a subnet mask in the protocol of TCP/IP Protocol. I know that the I.P Address is the one that identifies the computer in the network. But what I can't understand is why do we have to specify the subnet mask of a computer everytime you assign an I.P Address to a computer. Any site that can explain me this question

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The purpose of a subnet mask?

by Mackem In reply to The purpose of a subnet m ...

Hi.
Go to this link, you will find all you need to know about tcp/ip networks including subnets.
http://www.techrepublic.com/article.jhtml?id=t01820010529eje20.htm&src=search
Remove any spaces from the link.
Hope this helps
JV.

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The purpose of a subnet mask?

by den_santiago In reply to The purpose of a subnet m ...

The question was auto-closed by TechRepublic

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The purpose of a subnet mask?

by levick In reply to The purpose of a subnet m ...

Every IP address consists of two parts, one
identifying the network and one identifying the
node. The Class of the address and the
subnet mask determine which part belongs to
the network address and which part belongs
to the node address. Subnetting an IP
Network can be done for a variety of reasons,
including organization, use of different
physical media (such as Ethernet, FDDI, WAN,
etc.), preservation of address space, and
security. The most common reason is to
control network traffic. In an Ethernet network,
all nodes on a segment see all the packets
transmitted by all the other nodes on that
segment. Performance can be adversely
affected under heavy traffic loads, due to
collisions and the resulting retransmissions.
A router is used to connect IP networks to
minimize the amount of traffic each segment
must receive. Applying a subnet mask to an IP
address allows you to identify the network and
node parts of the address. Performing a
bitwise logical and operation between the IP
address and the subnet mask results in the
Network Address or Number. Additional bits
can be added to the default subnet mask for a
given Class to further subnet, or break down,
a network. When a bitwise logical and
operation is performed between the subnet
mask and IP address, the result defines the
Subnet Address. Subnetting always reduces
the number of possible nodes for a given
network.

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The purpose of a subnet mask?

by den_santiago In reply to The purpose of a subnet m ...

The question was auto-closed by TechRepublic

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The purpose of a subnet mask?

by levick In reply to The purpose of a subnet m ...

Every IP address consists of two parts, one
identifying the network and one identifying the
node. The Class of the address and the
subnet mask determine which part belongs to
the network address and which part belongs
to the node address. Subnetting an IP
Network can be done for a variety of reasons,
including organization, use of different
physical media (such as Ethernet, FDDI, WAN,
etc.), preservation of address space, and
security. The most common reason is to
control network traffic. In an Ethernet network,
all nodes on a segment see all the packets
transmitted by all the other nodes on that
segment. Performance can be adversely
affected under heavy traffic loads, due to
collisions and the resulting retransmissions.
A router is used to connect IP networks to
minimize the amount of traffic each segment
must receive. Applying a subnet mask to an IP
address allows you to identify the network and
node parts of the address. Performing a
bitwise logical and operation between the IP
address and the subnet mask results in the
Network Address or Number. Additional bits
can be added to the default subnet mask for a
given Class to further subnet, or break down,
a network. When a bitwise logical and
operation is performed between the subnet
mask and IP address, the result defines the
Subnet Address. Subnetting always reduces
the number of possible nodes for a given
network.

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The purpose of a subnet mask?

by den_santiago In reply to The purpose of a subnet m ...

The question was auto-closed by TechRepublic

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The purpose of a subnet mask?

by bluriz In reply to The purpose of a subnet m ...

The subnet mask identifies the network part of the address and the host machine part. ie in 10.1.2.30 address with a mask of 255.255.255.0 shows a network address of 10.1.2 and the host is at 30 whereas 10.1.2.30 with a mask of 255.0.0.0 shows a network address as 10 and the host is at 1.2.30. Hope that makes sense!

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The purpose of a subnet mask?

by den_santiago In reply to The purpose of a subnet m ...

The question was auto-closed by TechRepublic

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The purpose of a subnet mask?

by jo_ash In reply to The purpose of a subnet m ...

Another reason for using a subnet mask is to change the number of hosts available to the network. A class B network (eg 172.100.0.0) has 65534 hosts available. Subnet that using 255.255.248.0 (instead of the default 255.255.0.0) and now you've got2046 hosts available.

This allows you to split one class B network into multiple subnet masked networks.

Why do you have to specify the subnet mask everytime? Most operating systems will default, and you only have to enter anything if you wish to change it. What o/s are you using?

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The purpose of a subnet mask?

by den_santiago In reply to The purpose of a subnet m ...

The question was auto-closed by TechRepublic

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