Subnet ?

Hi, I just found this forum and I hope it is OK to ask a question on my first post.

I am taking a network engineer course and am currently studying net+. We just went went over subnets and I have a question hopefully someone here can explain to me so I can finally understand it.

According to the Thompson Net+ manual on page #571 in a class B you can create subnets of 2,6,14,30,62,126,254,510,1022,2046,4098,8190, and 16,382. How do you get these numbers? Also if I understand it correctly, you can't create a subnet of 5?

I am sorry if this is a ridiculous question but I have been beating my brain trying to figure it out for 2 days now and I give up. I need help.

Thanks in advance.
Steve

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Comments

Jiggsaww

The formula is 2 to the number then subtract 2 (2n-2)...........example if you are using 5 bits then 2(5) = 2x2x2x2x2 = 32 - 2 equals 30.....

Webmaster

Hi, I just found this forum and I hope it is OK to ask a question on my first post.

Of course it is, that's exactly what these forums are for. Welcome on board btw!

I suggest starting with www.learntosubnet.com, I think it will clear up a lot. Don't worry about not being able to fully grasp subnetting when you start learning it, but eventually, you have to be able to do this by heart as it is one of the very most important subjects for the CCNA, other Cisco exams, as well as networking in general.

And don't hesitate to post more questions if you have any.

xcanuc

Thanks for the help. I passed my Cert on Friday. Now it is on to A+.

Thanks again.
Steve

mikej412

xcanuc wrote:

I passed my Cert on Friday. Now it is on to A+

Congratulations!

And good luck with A+

nuglobe

I suggest starting with www.learntosubnet.com, I think it will clear up a lot.

Nice link, thanks.