classB subnet answer

taocircle asked about class B subnetting. I dont have much time so I did a quick and dirty answer for the question he asked. After watching what I did Ive determined that this is a pretty crappy explanation in my opinion, and so I may just go and do some decent general subnetting explanation videos eventually but for now heres what you got. hope it helps taocircle.

Category:

Howto & Style

Tags:

• classB
• subnet
• answer

[nawkwan]

Hi systemerror11,

The 3rd octet with the value '89' lies between 88 and 92, why are you choosing 88 and not 92? What happens if the number was 90 (which is the midpoint of 88 and 92), what would it be?

Thanks!

[systemerror11]

@nawkwan in that example 88 and 92 are network addresses. That means that all the numbers in between are possible host addresses (89,90,91)

Since 89 is higher than 88 (which is a network address) and before 92 (the next network address) that means its in the 88 network. Thats because everything after 88 is in the 88 network until you get to the next network, which is 92.

If the number was 90, that is still in the 88 network because it does not fall past (or into) 92. I hope thats a bit clearer.

[mark1192]

i found this helpful too. but what is the broadcast address of that network? im pretty confuse on getting the broadcast.

[systemerror11]

@mark1192 The broadcast address would be the last possible address before the next network - so in this case it is 172.29.91.255

I hope that clears it up for you.

[emgarc1982]

You are an asset to the human race.

I could not work out a Network address for an IP with a /19 address until I found this video.

[systemerror11]

Ha ha, I am glad you found it helpful. Ive been called many things throughout my life but an asset to the human race is new. I'll put it on my resume. :)

Thanks!

[nawkwan]

@systemerror11

Concurs with an earlier comment: "So bloody helpful thanks mate" ^^

[mrr344]

so bloody useful thanks mate

[Darkmanskin]

HELP!!! Network ID 150.50.0.0 Required number of subnet is 125

[emgarc1982]

I'm currently doing a CCNA and the material only had examples for /25 and up. Everyone you speak to knows how to work out a subnet if it's above /25.. so when I mention a /22 or /19 they clam up. I sat through an hour long Subnet lecture from some Indian university and all examples were for /25 and up. You just shot past the BS and got on with an actual example and I know how to work it out now for myself. Really grateful. So I'll name my first born systemerror11.