Subnetting Speed for ICND1

up2thetime

Hey just need some advice from anyone who has taken ICND1 (or 2).

I am thinking about going for it in a few weeks, but wondering, what you think is the recommended time one should be able to subnet in (figure out ranges/reverse engineer)?


I am able to do the questions from sub netting questions dot com correctly in less than 30 secs, but not sure if that will be sufficient enough for the ICND1.


Thanks for your feedback.

miller811

up2thetime wrote: »

Hey just need some advice from anyone who has taken ICND1 (or 2).

I am thinking about going for it in a few weeks, but wondering, what you think is the recommended time one should be able to subnet in (figure out ranges/reverse engineer)?


I am able to do the questions from sub netting questions dot com correctly in less than 30 secs, but not sure if that will be sufficient enough for the ICND1.


Thanks for your feedback.

not sure of the difference between ICND1 or 2, since I went the one test route. But you should be able to comfortably subnet in your head in my opinion. You can still write it out on paper to verify.

What method are using to subnet?

Neeko

30 seconds will be okay, but keep practicing because there are shortcuts to make it easier and the more you practice the more you will be able to just know certain multiples and it happens even quicker. Like miller said, should be done in your head really.

up2thetime

Hey,

For the most part I am using the method from Todd Lammle, although I am experimenting with a few other methods (and trying not to mix them all up!).

When reverse engineering, I take the subnet mask, subtract it from 256, and use the result as the increment.

When figuring out the number of hosts or networks I need, I count (2, 4, 8, 16, 32, ect) until 2^n or (2^n)-2 is satisfied, then look at how many bits it took.

It's worked pretty well for me as I am able to do it mentally now, but not sure if I am fast enough for the exams.

Still practicing like crazy. I occasionally get easy ones which can be done almost instantly.

LarryDaMan

IMO, if you can do them in 30 seconds you will be fine. I think most people do okay with the time constraints on ICND 1 and 2.

nelsonnr

Yeah - I did the ICND1 on Friday 19th June. 30 secs is fine. But make sure you are confident in your answer in 30 secs, any more and you'll be eating time.

I had 6 seconds to spare when I clicked the finish button. I need to improve my time management skills! Scored 874/1000

Good luck!

kevin31

up2thetime wrote: »

Hey,

For the most part I am using the method from Todd Lammle, although I am experimenting with a few other methods (and trying not to mix them all up!).

When reverse engineering, I take the subnet mask, subtract it from 256, and use the result as the increment.

When figuring out the number of hosts or networks I need, I count (2, 4, 8, 16, 32, ect) until 2^n or (2^n)-2 is satisfied, then look at how many bits it took.

Hi

can you go into more depth please on how you work out how many hosts? Also few quick examlpes please?

Ive been trying to understand subnetting for far to long now!

Thanks

Kev

up2thetime

nelsonnr wrote: »

Yeah - I did the ICND1 on Friday 19th June. 30 secs is fine. But make sure you are confident in your answer in 30 secs, any more and you'll be eating time.

I had 6 seconds to spare when I clicked the finish button. I need to improve my time management skills! Scored 874/1000

Good luck!

Thanks! Congrats on the pass!

kevin31 wrote: »

Hi
can you go into more depth please on how you work out how many hosts? Also few quick examlpes please?

Kevin,

Did you mean how to work out the number of hosts when you are given the subnet mask?

Or did you mean how to determine a subnet mask when you are told how many hosts are required?

Example: If I am given a Class C Address with a Subnet Mask of 255.255.255.240, then I know I have 4 free bits in the last octet for hosts since 240 is made up using 4 bits.
Knowing I have 4 bits for hosts, I just sub 4 into the formula (2^4)-2 and get 14.

Example: If I am given a Class C Address and told that 26 hosts are required per subnet, then I would keep swapping in values into the formula (2^n)-2 until the requirement is met. You can do this just by counting 2, 4, 8, 16, 32, ect, and then subtracting 2. So to get 26 hosts we need 5 bits as (2^5)-2=30 and (2^4)-2 will not suffice. Since 5 bits are being kept for the hosts, then 3 bits remain (the 3 leftmost bits in that octet) for the networks. This will result in the last octet being 11100000 which converts into 224. That is how you end up with 255.255.255.224



Everyone has a method that works really well for them, but it only works well after lots of practice. This method is what I find the quickest so far. I hope that helps.

sandman748

LarryDaMan wrote: »

IMO, if you can do them in 30 seconds you will be fine. I think most people do okay with the time constraints on ICND 1 and 2.

I partially agree with the above.

30 seconds for the simple subnetting questions is fine for the ICND1. I found 90 minutes to be more than enough time overall. ICND2 on the other hand cuts your time down to 75 minutes and starts throwing route summarization and VLSM at you. At that point the simple "what subnet does 172.16.31.37/28 belong?" type questions need to be much quicker as it's almost like doing several of those in one question.

up2thetime

sandman748 wrote: »

I partially agree with the above.

At that point the simple "what subnet does 172.16.31.37/28 belong?" type questions need to be much quicker as it's almost like doing several of those in one question.

Working on getting it down to 15-20 secs mentally

stlsmoore

I also say 30 sec. or less is good and this is coming from someone that on both tests wrote each subnetting question down on paper. At least get good enough to where you can do any Class C address in your head or without to much thinking. I wrote out the subnets on my sheet during the test just to double check that I had everything right plus I didn't have to keep track of what ranges and all that good stuff were in my head.

Make sure that you take as many shortcuts as possible to get to your answer that was my secret to cutting down my time. When i first started subnetting I wrote the complete solution out on paper and it took damn near half a page per question at first. Then I got to a level where I would know exactly what the question is asking for and would only use a couple of lines on a piece of paper to get to my answer.

Satcom

these threads are really helpfull...

davidspirovalentine

As long as you can subnet in your head in about 20 sec you should do fine... I passed ICND1 with 958/1000 and I owe it all to this site!!!

The guys on here told me to learn subbneting so well that you can do it in your head... Trust me it helps!!!

Also learn your 16 times table off by heart!!!

Good Luck!!! Im on ICND 2 now... sitting it on the 7th of september...

Regards,
David