Designing a subnet mask

How do you determine the proper subnet mask based on the below question??
You are designing a subnet mask for the 10.0.0.0 network. You want 4000 subnets with up to 4000 hosts on each subnet. What subnet mask should you use?

answer: 255.255.240.0

How is this answer determined?

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Comments

Monkerz

Click here --->http://www.techexams.net/forums/ccna-ccent/38772-subnetting-made-easy.html

instant000

BurkeJax wrote: »

How do you determine the proper subnet mask based on the below question??
You are designing a subnet mask for the 10.0.0.0 network. You want 4000 subnets with up to 4000 hosts on each subnet. What subnet mask should you use?

answer: 255.255.240.0

How is this answer determined?

Could you show how much you understand about it already? Then, we can just fill in the gaps?

themagicone

Simple answer:
2 ^ number of masked bits = number of subnets, 2 ^ number of unmasked bits - 2 = number of hosts. /16 = 2 ^ 16 = 65,536 subnets, 65,534 hosts per subnet. But that isn't taking into account classes.

Now, in the question 10.0.0.0. You need 4000 subnets, what power of 2 will do that for you? 2^12 = 4096. So 12 bits plus the class A bits (

gives you a subnet mask of /20. /20 = .240 or 255.255.240.0 Taking it further, what is the step or block size per subnet? second octet = 1, third octet = 16. 10.0.0.1 - 10.255.240.254 I believe would be the range. <-- someone check this part, thanks.

Following that try this:

172.16.0.0, you need 550 subnets. What mask will you use?

ccnaomkar

no of subnets
4000

2^k >4000

k=12

k=subnet bits

host bits=32-(default+subnet)

host bits=32-(8+12)

host bits=12

as question

u asked subnet mask

255.255.240.0

ccnaomkar

https://learningnetwork.cisco.com/servlet/JiveServlet/previewBody/6014-102-1-19236/Subnetting%20Examples.pdf