For CCENT, should I memorize raw # of hosts/networks per class?

nopixel

I know that understanding/memorizing the octet range, valid network numbers and total number for a class (2^7, 2^14, etc) are important for the exams. My question is, should I memorize long numbers like 2,097,152 (total number of networks for Class C) and 16,777,214 (total number of hosts for class A network)?

I'm curious if knowing the exponential values is sufficient. I know this sounds like nitpicking but I feel like i'm already forgetting more than i've learned.

Back to ....

DoubleNNs

Just take a few minutes to memorize all the numbers. You only need to be familiar w/ them, not be able to recall them completely off head.

During the exam, you can always do the math on your whiteboard. Just go with the highest number you know by heart (could even be as low as 256) and multiply by 2 until you get to the number needed. Being familiar w/ how the numbers are SUPPOSED to look helps you realize if you messed up on the math at any step.

Other than that, I don't think you should spend a lot of time memorizing those specific numbers. And I doubt the exam is going to throw any huge number at you, such as something in the millions. Just make sure you practice your subnetting extensively and you'll be fine.

NetworkVeteran

nopixel wrote: »

My question is, should I memorize long numbers like 2,097,152 (total number of networks for Class C)

No. It's more important to understand how to derive those numbers.

E.g., in 1-3 seconds, total number of hosts on a Class A network is 2^24 = 2^4 x 2^20 = 16 x ~1,000,000 = ~16,000,000.

theodoxa

I only memorized up to 65,536. But, even that is probably well beyond what you would be expected to know to the digit. Beyond that, I can calculate the numbers by multiplying/dividing. I know that 10^24 is roughly 16.7 Million and 10^32 is roughly 4 Billion. I doubt they'll try to mess with anyone by giving multiple similar options for very large numbers. The odds are that any options other than the correct one for very large numbers will be far enough off that knowing the rough numbers will be sufficient to pick the right one. I also doubt you will see too many very large subnets. The largest subnet I've ever seen in a real network was a /22.

I would suggest memorizing /8, /16, /22, /23, /24, /25, /28, and /30.