CCENT Preperations

I am have finished ICND1 book from Cisco and half way through my CCENT examcram but I STILL cannot get comfortable with subnetting, I cannot feel confident about taking this exam knowing that I am having a difficult time with this. I am wanting to take this exam so that I can attend the network academy at a local community college to help prepare for the second exam. Any advice? I have looked at a dozen pieces of material, everyone seems to explain this process differently and I seem to be more confused. I feel like I may be one of the only ones out their having this many problems but it just wont click...

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cisco_kidd

rolyohh wrote: »

I am have finished ICND1 book from Cisco and half way through my CCENT examcram but I STILL cannot get comfortable with subnetting, I cannot feel confident about taking this exam knowing that I am having a difficult time with this. I am wanting to take this exam so that I can attend the network academy at a local community college to help prepare for the second exam. Any advice? I have looked at a dozen pieces of material, everyone seems to explain this process differently and I seem to be more confused. I feel like I may be one of the only ones out their having this many problems but it just wont click...

See if this will help

http://www.techexams.net/forums/ccna-ccent/38772-subnetting-made-easy.html

rolyohh

Thanks! I will check it out tonight and hammer away at all of the subnet questions that have gone unanswered.

cyberguypr

The exact same thing happened to me. I got confused after seeing 100 different ways of subnetting. The link cisco Kidd posted above was the missing piece that solved my problem. Read that, ask if something is unclear and then go practice as much as you can. I was amazed that after a few weeks I was able to subnet with no paper, calculator or anything, just in seconds.

lrb

You are most definately not the only person who subnetting wouldn't click for straight away, which is probably why Cisco hammers it on the ICND1 exam. Subnetting and ACLs are two of the most fundamental skills in networking. Take the time to really really learn both and you will be a much better networker for it, both in your day to day job and cert exams.

Blackout

I seriously dedicated 3 weeks to learning subnetting, I would do subnetting questions at the house before work, if I had a break at work I would subnet, I would go home after work and subnet untill bed time. I litterally have memorized block sizes and can subnet in my head. Pick a method and stick to it, I personally really liked Jeremy's method from CBTnuggets, but its not for everyone.

MrXpert

I used the Sybex net+ guide to learn subnetting. I know there's other methods out there but I found them confusing.
I can subnet in my head usually in about 15 seconds, It does take practice and lots of it for most of us to see the patterns. Unless of course you are John Nash

MrBrian

I used the method that Todd Lammle uses in his CCNA book. I don't really know why, but that's just the way that really made it easy for me, and it stuck. Basically, given any mask such as .224, .240,. .248, .252, for example, you just subtract it from 256 to give you the subnet increments (also referred to as block size).

For example, you have 192.168.50.0 with a mask of 255.255.255.240... just do 256-240= Block size of 16 in the 4th octet...
This means you're subnets will be 192.168.50.0, 192.168.50.16, 192.168.50.32, etc.. Whenever I see 240 I think block size of 16.. Whenever I see 248, I think block size of 8.. And with 252, I think block size of 4 (256-252=4).. etc. Just subtract it from 256 to get your increments. And this is why point to point links will typically use a .252 in the 4th octet (aka /30).. You don't need to give it a block size of, say, 32 IP's, because there's only 2 interfaces on it.

For those host-range and broadcast address questions it's easy.. the broadcast for each subnet is the number right before the next subnet. For the 192.168.50.16 subnet the broadcast address will be 192.168.50.31 (because the next number is the next subnetwork). The host range for this subnet is 192.168.50.1 - 192.168.50.30 (the last host is 1 before the broadcast of the subnet).

Here's another typical question, and good skill to know.. say they give you an IP and a mask.. but the IP isn't a network, rather some host inside a network. You should be able to determine the network that that host resides in. For example, you get 192.168.10.73 with mask 255.255.255.224... A quick way to solve this is by first finding the block size.. 256-224=32 (so every 32 numbers in the 4th octet, it's a new subnet). So for subnets, the number in the 4th octet has to be 0, 32, 64, 96, 128, etc. Well, what subnet is the .73 host fit in? Yup, the 192.168.10.64 subnet. After awhile it gets quick and easy because there's only so many masks you can possibly see

Anyways, I hope this could help or clarify, and not further confuse lol.

rolyohh

Thanks for taking the time to type that up. I have successfully answered several questions after reading this. Why this subject is so difficult and why are there so many methods is beyond me. Just glad I feel comfortable. Now I will practice!

MrBrian

Yea no problem.. I know the stuggles, trust me! Having since "seen the light" I enjoy trying to help others as well

soooowutnow

One thing that helped me during the test was writing down the subnetting increments on my dry erase board prior to taking the test while i waited for it to load. Mine looked like this:

128 64 32 16 8 4 2 1
192 224 240 248 252

Then in case I needed it I also put, 256 512 1024 2048 4096 8192 16K. (For host and subnet questions).

Also I put 11111111 11111111 11111111 00000000 = /24
11111111 11111111 11111110 00000000 = /23 etc etc etc

This was an easy reference guide and I got the idea from Jeremy from CBT Nuggets. He says to ask for an extra dry erase board so you can do this at the beginning and then refer to it. It is not cheating in any way because it comes from your head, not the book. Also it really saves you time during the subnetting questions.

Just my 2 cents.

Tinov

There are some subnetting practice questions at: Free CCENT questions. I found that lots and lots of practice was the best way to increase confidence, which is absolutely essential in the exam.

jude56g

Subnetting never really clicked for me until I watched Jeremy's CBT nuggets. He breaks the process down in a way that made sense to me. Reading the process from the books made me want to pull my hair out. Check out the nuggets videos if you can, and just practice away. It will eventually sink in, but in my experience is takes most people a while to wrap their heads around it.. so don't get discouraged.

alxx

The trick is to take your time and don't try and rush it.

Stick with one method, get very familiar with it and just keep practising until you can do it without thinking about it.