IP Addressing and Subnetting

Posted on 2013-09-21
Medium Priority
Last Modified: 2013-11-05
I am rusty when it comes to IP addressing and Subnetting.  Give me some good resources to look at - if there something better than what you find outside of googling it,

I have my firewall / gateway for the internal network.  I do I assure that mapping of drives from the wireless to the internal network itself is seamless.  

and explain subnet mask more to me: vs vs
outside the question just extra knowledge for me.  I know it gives more IP choices and range and muilti casting etc... But I forget???

The real thing I need now is this:

Seeing printers, mapped drives, any resource on the internal IP range.


Internal:  192.168.5.XXX

Normally you give the wireless router an IP from the range for its IP and then give it - its range for DHCP on the wireless.

Wireless WAN IP:  192.168.5.XXX

LAN IP: 10.1.10.XXX

2 things - is it better and what makes it seamless to use 192.168.6.XXX

same 192.168.xxx.xxx or ???

Question by:Clint Jones

Expert Comment

ID: 39512248
LVL 17

Expert Comment

ID: 39512981
Wikipedia, has some articles.
You have "routing for dummies " or for beginners pages too:

A subnet calculator is handy:

Now for your question, why do you want separate subnets for wired and wireless network? You can use the same subnet for both, and then you don't have to route packets between wireless and wired. This will make it easier for each node to see the other nodes.
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Accepted Solution

CompProbSolv earned 2000 total points
ID: 39513670
Your IP (v4) address has two parts: the network and the host.  Devices can only connect directly with other devices using the same network number.  Otherwise, they need to send packets to a gateway.

The netmask determines which part of the address is network and which is host.  It is done in a binary fashion (one bit at a time).

To keep it simple, start with netmasks that only use 255s and 0s.  If you have a netmask of then the first octet (numbers before the first period) exactly specify the network.  The following are on the same network when a netmask is used (because they all start with 192.):

If a netmask of is used, then the first two octets determine the network.  Using the same set of IP addresses, only these are on the same network (because they start with 192.168.):

If you switch to a network, only these two are on the same (start with 192.168.1.):

Each octet can have a value of 0-255 (though some are excluded at different times).  Each one can be seen as an 8-digit binary number.  If you compare (mask) the IP address with the netmask (using the binary representations), wherever you find a 1 in the netmask, that bit is part of the network.  Where you find a 0, that bit is part of the host.  Using the 255s makes it easy because that is all 8 bits as 1s.

The gets slightly more complicated, but really follows the same scheme.  248 is 1111 1000 in binary.  That means that with a network, the last three bits of each IP address specifies the host.  For example, assume one of your network addresses is  The other hosts on the same network will be through  The .0 and .7 are excluded as you are not allowed a host address with all 0s or 1s.

It is helpful to convert to binary for other addresses.  For example, if you have a address, it is not obvious what else is on the same network.  54 is 0011 0110.  The other devices on the same network will have all but the last three bits the same, so they will range from 0011 0000 to 0011 0111.  Remembering that the all 0s and all 1s for hosts are not allowed, that really leaves 0011 0001 through 0011 0110 or 49 through 54.

There is also one other notation type for netmasks.  Assuming that the netmask starts with 1s and ends with 0s, you can just count the number of 1s.  A netmask of can also be written as /24.
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LVL 17

Expert Comment

ID: 39514687
As posted in the first solution, start with youtube. You might grab fast because it's audio/video. Most times I saw beginners in a drowsy mood while listening to ip subnetting lectures........ :)

Todd Lammle has something called "subnetting in your head". You can see the result in google. If you can grab his technique, you will never need any pen/paper/calculator for subnets, ever.


Author Comment

by:Clint Jones
ID: 39530324
Thanks you for your help I am reviewing all the data now...
LVL 18

Expert Comment

ID: 39530339
The best IP Calculator I  have found is ipcalc.

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