CCNA level first test

Tomorrow I have my first test for subnetting and cidr notation convertation. We have to convert between cidr, subnent, host and max hosts.. I'm wondering if anyone could point me in the right directions or through some examples up and walk me through without giving it away... Due to aspergers math is not my strong point...

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Freestuff212

You should check out subnetting.net - Subnet Questions and Answers

jvrlopez

Ask for subnetting help and you'll get about 20 different answers and methods on how to do it. I'd share mine but I'll save you from the onslaught on forecoming replies...but I will concur with the above site. Practice those everyday and you'll eventually pick up the pace and confidence when it comes to subnetting.

At the minimum, I can recommend that you are sure about your powers of 2, block sizes, and CIDR notations. Also, don't forget to subtract 2 for your network ID and broadcast addresses!

CiscoDidit

I flip flop between the site mentioned earlier and subnettingquestions.com - Free Subnetting Questions and Answers Randomly Generated Online

The Silent Assassin

This was the area that I was feeling the least confident about. The method can be broken in to four steps. Find the bits, reserve the bits, find increment then use increment to find the ranges the ranges. For example if you need 2 hosts per network you will have an increment of 4 when doing the ranges. One will be the DG and the other will be the broadcast out of the block of 4 and you will have a 255.255.255.252 SM or x.x.x.x/30. I suggest you try to follow that method until you learn the notations and that only comes with practice and time.

Reverse engineering is the easiest way and will be the most common where you see the CIDR notation only and be asked to find valid ip addresses in a range or two or more addresses that belong to the same network.

Example: 192.168.10.0
Req: 50 Networks = 2 Hosts

Step 1: Convert the req to binary.
50 = 00110010

Step 2: Reserve the bits in Mask and find increment
255.255.255.0 = 11111111.11111111.11111111.00000000
255.255.255.252 = 11111111.11111111.11111111.00110010

Step 3: Use increment to find ranges(always the lowest bit in the mask)
Increment = 4

192.168.10.0-3
192.168.10.4-7
192.168.10.8-11
192.168.10.12-15
192.168.10.16-19
..
..
..
..
etc.

gbdavidx

Freestuff212 wrote: »

You should check out subnetting.net - Subnet Questions and Answers

In addition, should read this Subnetting Tips & Tricks

I also memorized 128 192 224, 240, 248, 252, 254 and 255 (how many bits are bottowed from each).

I also wrote this down

256, 128, 64, 32,16, 8, 4, 2 and (this will give you the answer to your power, 2^1 = 2, 2^2=4, 2^3 =8 ect, and just keeps doubling
128 64 32 16 8 4 2 1

this will help you find what is 2^X this helped me get a perfect score on subnetting in CCENT

MAC_Addy

There are so many different ways to subnet. Honestly, look at what people are posting on here, and one of these will definitely work for you. Find one that does work for you, and practice, practice, PRACTICE!

When I was first getting into networking, I always heard that subnetting was difficult. So when I started starting ICND1 I actually skipped subnetting thinking that it would be tremendously difficult. The most difficult part was me thinking it was difficult. I went back, learned it, and have never had any problems since. My pro tip is don't think that it is difficult, because it's not. Though, finding something that'll work for you might be a little challenging, but you'll get there in the end.