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IP subnet mask questions

jppinto
jppinto asked
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Last Modified: 2012-06-27
Hello,

I've a computer with IP 191.1.12.129 and there are 2 subnets defined. I need help with the following questions:

- How many bits are used for the subnet mask?
- How many bits are used for hosts addressing?
- How many subnets are not used?

Thanks in advance for your help. I'm new to networks and I really need your help.

jppinto
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"Batchelor", Developer and EE Topic Advisor
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Commented:
Hello,

I know that this IP address is a class B subnet...at least that I know :)

I need to know the rest of the information.

jppinto
Qlemo"Batchelor", Developer and EE Topic Advisor
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Commented:
As I said, use that calculator site. And some common sense. A mask of 255.255.0.0 is how much one's bits from start (left)? The answer is: 16. That is the same with each Class B subnet.
Host bits are all bits that are zero, counted from right. Again, this are 16.

I cannot answer the rest, because your question is not complete. What IPs do your 2 subnets consist of?

Commented:
on that computer if you run command

ipconfig /all (winodws)
ifconfig -a (*nix)

what is teh output?
Fred MarshallPrincipal
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What do you mean by "there are two subnets defined"?  Please illuminate.
I can't tell you what this is, this was the information I was given...

It depends on the subnet mask
I believe the subnet mask is 255.255.128.0 (using the calculator)

Qlemo"Batchelor", Developer and EE Topic Advisor
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Guessing does not help. You need to know, else you (and we) can't answer the questions.
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This is a real situation that I got stuck in! This is not clearly my area of expertise! I was asked for help from my boss and even after I told him that this is not my area, he still insisted in my participation!

I will try to learn a little more about this and will read the material at the link you recommend. I will tell him that I can't answer the questions he asked me and will close the question by awarding the points to all that participated and will not spend more time with this. As you all said, this is a little like "shooting on the dark" and without more information it's hard to give him a correct answer.

Thanks for the help.

jppinto

Commented:
My deepest sympathy, and the very best of luck!

If I can give you some pointers for a future question on this matter:  Indicate where the information ("computer with IP 191.1.12.129 and there are 2 subnets defined") comes from.  Is it a verbal message from your boss, or a phrase in a supplier's documentation or a test report from a work colleague?  This will assure that responses will be applicable to your situation.

My other concern is the nature of the questions itself:  I know of no specific application where it is required to specify the number of bits used for networks or hosts, or the number of unused subnets.  Usually it is only used in quizzes to test knowledge of subnetting.  Again, knowing the source of the question could provide some clues.

Let us know if you have any update on the issue!

Author

Commented:
Thanks for your support... :o)
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