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Question how to apply the formula (2^h -2>=number of available IP addresses)

Gojarz

Junior Member
Dec 6, 2020
1
0
6
Hello everyone. How can someone apply the formula (2^h -2 >= number of available IP addresses) to an IP address? The formula is for calculating how many IP addresses can be in a sub-net. I searched a lot and didn't find any good tutorials on how to apply it and how it works.
 
Last edited:

mxnerd

Diamond Member
Jul 6, 2007
6,152
887
126
h = 10


1st network will be 180.40.0.0/22, 1st host 180.40.0.1, last host 180.40.3.254
2nd will be 180.40.4.0/22
3rd will be 180.40.8.0/22
64th will be 180.40.252.0/22, 1st host 180.40.252.1, last host 180.40.255.254


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MtnMan

Diamond Member
Jul 27, 2004
6,637
4,904
136
I know it's his homework. Subnetting is hard for starter. So giving him a hand.
I taught subnetting as part of CCNA training for years. Linking them to a crutch (subnet calculator), just guarantees they will continue to use the crutch instead of developing an understanding.
 

mxnerd

Diamond Member
Jul 6, 2007
6,152
887
126
I taught subnetting as part of CCNA training for years. Linking them to a crutch (subnet calculator), just guarantees they will continue to use the crutch instead of developing an understanding.
I absolutely don't want OP to use subnet calculator. The reason I gave OP the link to subnet calculator and show him how the subnetting should be done is because the subnet calculator clearly show the whole picture. He then need to use his pen and paper to practice and understand how it works.

I took CCNA class before, and one of the instructors just don't know how to teach.
 

MtnMan

Diamond Member
Jul 27, 2004
6,637
4,904
136
I took CCNA class before, and one of the instructors just don't know how to teach.
They exist, I worked with one... I had his former students that couldn't subnet, so we had remedial subnetting exercises till they got it.

They were easy to sort out. After calling roll on the very first day, I gave them an exercise to design, build, and configure a network to ping from PC to PC across 3 routers in series, and they were only allowed to use addresses in the 192.168.1.0/24 network. They could use static or dynamic routing.

topology
(PC)--------(RTR)---------(RTR)---------(RTR)---------(PC)​

My previous students typically knocked it out in 20 minutes. His previous students, not so much, most couldn't do it. But I got them caught up by doing subnetting drills to start every class for a couple of weeks.
 

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