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Home > Archive > 70-210 > August 2002 > Subneting tricks for everyone
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Subneting tricks for everyone
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| Riverwind6 2002-08-03, 8:29 pm |
| Hi,
I saw a lot of posts with people asking how to subnet or trying to give ressources where subneting can be learned easily...
I think subneting is really not that hard. Especially with these little tricks.
For the following question:
What is the range of valid IP addresses if you have the address 192.168.0.76 with a subnet mask of 255.255.255.224
The trick is to break this question in easy parts.
The first thing I ALWAYS do is find out the magic number. The magic number helps you find the addresses of all the subnets. To find it, you substract the subnet the last part of the subnet mask from 256. Here it's 256-224=32. So 32 is our magic number.
Then you go 0+32=32. 32+32=64. 64+32=96 and so on. And this gives you the subnet addresses.
192.168.0.0
192.168.0.32
192.168.0.64
192.168.0.96
192.168.0.128
192.168.0.160
192.168.0.192
192.168.0.224
192.168.0.256
Now you can't use 192.168.0.0 because its the zero subnet. And you can't use 192.168.0.256 because its not valid.
From there you know where each range begins and ends. And its easy to find all the info you need to answer the question.
Our address was 192.168.0.76
By looking at the table we just created, you see that it belongs to the 192.168.0.64 subnet. So the range of IP addresses for this subnet is 192.168.0.64 up to 192.168.0.94.
The last thing is to remember that you can't use the first IP address of a subnet(subnet address) or the last one(broadcast address).
So the valid range of IP addresses would be 192.168.0.65 up to 192.168.0.93.
Thats it...
But the best trick, of course, is to practice. | |
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| dheinsdorf 2002-08-04, 1:08 am |
| quote:
Originally posted by freak
www.mcsefreak.com/subnetting.htm to understand why the above works 
Hi, I just bought your MCSA pack - looking forward to them! Anyhow I took 2151, the old NT4 Networking class and just passed NetTech (for CNE). The easiest method I found for that "magic number" was in the Exam Cram book for NetTech - The value of the rightmost "1" of the mask is the subnet. For "224" its "32", no need to subtract.
After 3 classes covering subnetting any many cram sheet downloads, the Author of that Exam Cram got me to sub/supernet where the other text didnt. | |
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| Cool! Thanks for the post. BTW, I emailed you the guides so they should be in your mailbox by now. Let me know if I can help! |
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