Anybody know anything about Subnet Masking!?!?

V

Voltrizzle

CAG Veteran
God, I hate doing these things... except this time... it is for a take-home test in my Networking class. :bomb:

Anyway... I need to create as many small networks as possible, but I only need 5 assignable IP addresses per network. He gave me the IP address of 200.10.50.0. I found the subnet mask of that (which is 255.255.255.224) and the broadcast address (which is 200.100.50.31).

Now, excluding the original network and broadcast addresses, I need to know the following:

How many subnets will I have?
What are the addresses of the subnets?
What are the device addresses for any ONE of those subnets?
What is the broadcast address for that subnet?
What is the new subnet mask?


If any of you guys could help me on that, it would be fricken incredible. I know I'm a newb, but I have a lot of information and knowlede to share... so it would be a help if somebody could maybe give me some pointers on this one :bouncy:
 
[quote name='Cornfedwb']Do your own homework....[/QUOTE]

Hey, thanks a lot!!! Anyway, anybody? Anybody at all... I am not looking for answers, I am looking for pointers on how to get those answers
 
Subnetting is easy and you did it wrong. The broadcast is always x.x.x.255 and the network ID is always x.x.x.0.
255.255.255.0 in binary is 11111111.11111111.11111111.00000000
I'm going to assume you know what binary is and how it works.
When ever you subnet, you can never (You can but its compicated) use the first and last ranges. The first is for the network ID *x.x.x.0* and the last is for the broadcast ID *x.x.x.255*
So the subnet X.X.X.128 cant work because it only makes two subnets. Heres a way to cheat with subnets.

11000000 is 192, but if you read it backwards, its 4. That means it breaks it into 4 chunks. However, as I mentioned previously, you cant use the first and last, that makes 2 available ranges. Here are the ranges:
0-63 - cant use
64-127 - can use 65-126
128-191- can use 129-190
192-255- cant use

You cant use 64/128 or 127/191 because those are the subnet IDs and the subnet broadcasts respectively.

128-64-32-16-8-4-2

2-4-8-16-32-64-128

Keep in mind that you may need to subtract 2. So if your teacher asks for 7 subnets, 255.255.255.224 would provide you with 8, so that'd work. UNLESS they ask for 7 *USEABLE* subnets, inwhichcase you'd need to go with 255.255.255.240. This is a very popular question used to see if you're paying attention to wording.

So I didn't give you an answer, but this should give anyone a basic idea how to solve it.
 
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