IPv4 Subnetting - Finding the last valid host in a network

[@TheCountryFamily]

The N1LB chart is pure genius, I had never heard of that. This video just saved me from failing my course. Thank you!

[@rainonmyface]

I have watched this video every time I forget how to do something. It's gotten to the point where I just go to the end for a refresher, but my networking course never really talked about an N1LB chart, and I really appreciate you defining it and explaining everything so clearly. Thank you.

[@anxiety9388]

My course sprinted through this part so I was lost. This video was a life saver, thank you!

[@MaheshPatil-yx5sx]

but some time add 1 for to right answer but why please explained

[@whatwhat177]

i like your N1LB chart. I've been through 3 video courses and have not seen anyone use that. It puts things in perspective. I'm going in to take my net+ today and thought id practice subnetting, and realized i didnt know how to find the first and last host ips, or the broadcast for anything than the /8, /16, /24. Thanks

[@PatrickHornung]

Glad it helped! Good luck on your test! :-)

[@whatwhat177]

Passed that test. These expensive CompTIA tests are so stressful, they take away the joy of passing.

[@Hotgarbage1913]

The N1LB chart makes this so easy, thank you for the help

[@faisalmahmud5794]

what will be if your last octet is belongs to 81 instead of 80???

[@truthtriumphs5289]

2:36 What do you mean by '32' does not fit? Could you kindly explain that

[@nathanlucas2257]

For anyone else wondering this, I had to find another one of his videos to get clarification. First, he sees if 128 fits into 80, which it does not, so he marks that as a 0. Then he sees if 64 will fit into 80, which it does, leaving a remainder of 16. He marks that position as a 1. After that, he is no longer seeing if power of 2 will fit into 80, but rather then remainder of 16. So 32 will not fit into 16...he marks that a 0. The next power of 2 is 16, which will obviously fit into 16...so he marks it as a 1.

[@PicksFromTone]

@@nathanlucas2257 Why'd he starts with 128 though?

[@nathanlucas2257]

@@PicksFromTone Each octet has 8 bits. Each bit represents 2^x where x is determined by the location within the octet. From left to right, it would be: 2⁷+2⁶+2⁵+2⁴+2³+2²+2¹+2⁰ So he's starting at 2⁷ which equals 128. Since 128 cannot fit inside of 80, he assigns it a Host bit (0) and carries over the "remainder" of 80. Then he looks at 2⁶, which is 64. Since 64 fits inside of 80, he assigns it a Network bit (1) and then subtracts 64 from 80 to get a remainder of 16. He then moves on to 2⁵ which equals 32. Since 32 does not fit into 16, he assigns it a Host bit (0) and you still have a remainder of 16. Then he looks at 2⁴ which equals 16. Since 16 fits into 16, he assigns it a Network bit (1) and there is a remainder of 0. So all other bits being inspected will be assigned a Host bit (0). Rather than writing down the above chart as "powers", I find it much easier to just quickly jot down all of the values on the side of my scratch paper. You start at 128 and each consecutive bit divides the value by half. 128 64 32 16 8 4 2 0 Hope this helps!

[@atomiswave2]

what if it is 2 octets u need to change?

[@KeytarArgonian]

This is incredibly useful!

[@johndewilde7422]

This is finally something I can understand. and do consistently. How is the block size calculated with this method for say a Class A address of 10.164.105.82 with a 255.255.224.0 mask? Is is possible? I was able to use your method for most of my calculations but I'm stuck on the block size. thanks for a great video

[@jacobcorson6527]

Thankyou understood perfectly

[@sumangautam1535]

192.168.10.255/24 is valid host or not?

[@raventhorX]

anyone ever use testout? seems pretty annoying with their pc pro course they have. my school is currently requiring me to use it and it has a lot of problems with it. almost to the point where it seems the questions and labs are impossible. It's surprising because I am also using the network+ version as well with another class and for some reason that one seems to not have any issues, or at least not as many. Well the reason im posting is this, it seems the program is not giving me enough information to finish certain labs, this has been common. Well in one lab I need to set up 2 different network adapters one of which will be used at a later date and seems to be installed fresh. One of the requirements is that I need to configure the host IP to be the last valid address on the subnet. Well, I dont have a flipping clue how to find out what the last valid address on the subnet was and so far I keep finding resources where a subnet mask and network address has been provided. this one does not show ones that have been used previously but rather ones i need to configure to currently.

[@lalithasadanandan2502]

N1LB🔥

[@dinorossi6611]

EVERYONE has their different confusing system

[@PatrickHornung]

That's the cool thing - pick the method that works for you. If my method doesn't work for you, that's cool! Everyone learns and remembers things differently. :)