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Is there any logic in using two different names for determining host ID and net ID?

For example, if you type print route in a Command Prompt you get things with netmask, but the IPv4 settings seems to use subnet mask.

Is there any significant difference between the two terms?

Hennes
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SpiXel
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2 Answers2

46

The difference is very, very slight. 9 times out of 10, they will mean the exact same thing.

However, the terms can have a contextual meaning in cases where we're discussing the subnetting of a given network. In those cases, the two terms "network mask" and "sub-network mask" can have distinct meanings. That is, if we make a distinction between a "network" and a "sub-network" then "the mask of a network" and "the mask of a sub-network" mean different things because of the context. This distinction is a relative distinction.

For example, let's say you've been issued the 10.10.0.0/16 network (using CIDR notation). Here, your "network mask" is 255.255.0.0. Let's say you need to separate this network into 4 smaller networks, each as large as they could possibly be. In order to get 4 networks out of 10.10.0.0/16, you need to borrow two bits (00, 01, 10, 11) from the host address and use them for the subnet addresses. This will give you the following sub-networks:

10.10.0.0/18
10.10.64.0/18
10.10.128.0/18
10.10.192.0/18

Here, your "network mask" is still 255.255.0.0, but each "subnet mask" is 255.255.192.0.

But, as I said, it's completely a relative term based on context. One could also talk about 255.255.192.0 being a "network mask" and then 255.255.0.0 being a "supernet mask" if in the same context we're talking about 10.10.0.0/16 being a supernet of, say, 10.10.64.0/18. It's all based on the context of what is being discussed.

Bacon Bits
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9

The "Netmask", "subnet mask", or simply "mask" are all the same thing: A mask that tells software which IPs belong to that network an which don't.

Darth Android
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    @SpiXel: Darth Android is correct. This is not really even up for debate. – jftuga Jul 26 '11 at 17:06
  • @SpiXel: Dividing a network into smaller parts may consist of using VLANs to separate and/or isolate traffic, such as DMZs, servers, HR, Marketing, Developers, iSCSI, backups, etc. – jftuga Jul 26 '11 at 17:08
  • @jftuga: yes that's right for the smaller networks part,Thank You :) – SpiXel Jul 26 '11 at 17:11