Subnet on the Fly..

D

DreadStarX

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I wasn't sure where to post this originally, but I was suggested that I post here.


As part of my CCENT, I need to learn how to Subnet on the fly. I need to be able to look at an IP, and figure out the subnet for it. I know that my IP Address at home is

"96.46.29.*** = 255.255.255.0". But what would 10.10.10.xxx be? I'm trying to get the hang of this before I even take the CCENT.



Thanks in advance!

- Thomas
 
Subnetting is extremely tricky at first, at least it was for me. What I recommend is simply practicing the different classes (A, B, C) over and over again. Give yourself different host targets, etc. Also, ignore people who say using a subnet calculator is bad. A good sysadmin can subnet without one, yes, but as long as you know how to do it without one (if you need to) it's absolutely fine to save time and use a subnet calculator.
 
Patrick said:
Subnetting is extremely tricky at first, at least it was for me. What I recommend is simply practicing the different classes (A, B, C) over and over again. Give yourself different host targets, etc. Also, ignore people who say using a subnet calculator is bad. A good sysadmin can subnet without one, yes, but as long as you know how to do it without one (if you need to) it's absolutely fine to save time and use a subnet calculator.
Click to expand...

I would love to do it as you said, Patrick, but for the CCENT, I have to be able to do it by hand, and within 3 - 5 minutes. This is one of the goals my instructor has given me to work on before I get to part 2 of the CCENT.
 
Last edited by a moderator:
Of course, that's why I mentioned practice. In the real world though, on the job, a subnetting calculator is fine granted you're comfortable doing subnetting without one. You don't want to rely on it.
 
0.0.0.0 to 127.255.255.255 is class A which by default makes it 255.0.0.0
128.0.0.0 to 191.255.255.255 is class B which by default makes it 255.255.0.0
192.0.0.0 to 223.255.255.255 is class C which by default makes it 255.255.255.0

But you can use whatever subnet you want if you customise it to your own choosing.

or am I missing something? I've never heard of CCNET so don't hurt me.

It's when you have 10.10.10.10/15 that you need to calculate the subnet to a more difficult standard

 

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