# Featured Posts

#### Posts from ‘IP Addressing – VLSM’

WARNING: You must master subnetting using our course or some other trusted materials before you start using these shortcut approaches. It is a common issue for Cisco candidates to move directly to subnetting shortcuts for the exams without fully understanding exactly how subnetting functions.

ICND1 (CCENT)

Question 3: Your co-worker has decided upon use of the 172.16.0.0 address space for a section of your network. This section requires 15 subnets. What subnet mask will you recommend?

Step 1: I reference the Powers of Two chart I created on my scratch paper when I encountered the first question. The forumla for the number of subnets you can create based on subnet bits is 2^s. From the chart I see if we “borrow” 4 bits we can create 16 subnets.

2^7=128  |  2^6=64  |  2^5=32  |  2^4=16  |  2^3=8  |  2^2-=4 | 2  ^1=2  |  2^0=1

Step 2: Borrowing 4 bits beyond the Class B boundary results in 255.255.128+64+32+16 = 240. Our mask is 255.255.240.0.

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WARNING: You must master subnetting using our course or some other trusted materials before you start using these shortcut approaches. It is a common issue for Cisco candidates to move directly to subnetting shortcuts for the exams without fully understanding exactly how subnetting functions.

ICND1 (CCENT)

Question 2: You have run the ipconfig command and discovered your IP address and mask are 192.168.20.102 and 255.255.255.224. How many hosts are permitted on your subnet?

Step 1: I reference the Powers of Two chart I created on my scratch paper when I encountered the first question. Adding 128 + 64 + 32 = 224. There are 3 bits used for subnetting and that leaves 5 bits for hosts.

2^7=128  |  2^6=64  |  2^5=32  |  2^4=16  |  2^3=8  |  2^2-=4 | 2  ^1=2  |  2^0=1

Step 2: The equation for the number of hosts per subnet is 2^h – 2 where h is the number of host bits. From the chart I see that 2^5  = 32. 32-2 = 30 hosts per subnet! Too easy!

As always, let us know in the comments if you have a quicker approach.

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Thanks to Randy of our CCNA program for this suggestion. Randy wanted some guidance on how to solve the subnetting questions in ICND1 and ICND2 very quickly. The ability to do this is often the difference between a passing score and a failed attempt.

WARNING: You must master subnetting using our course or some other trusted materials before you start using these shortcut approaches. It is a common issue for Cisco candidates to move directly to subnetting shortcuts for the exams without fully understanding exactly how subnetting functions.

For this series of posts, we will use simulated exam questions from ICND1 and ICND2. Well, with all that out of the way – let’s have some fun. You will find that once you “turn the corner” on subnetting, you will pray for many of these questions in the exam. It is an opportunity to solve questions quickly and be 100% convinced that your response is “spot on”.

ICND1 (CCENT)

Question 1: What is the last usable address in the subnet of a host with the address 192.168.1.134 and the subnet mask of 255.255.255.240?

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As you may have noticed, INE does a wide variety of training in the Cisco space.      This blog post goes out to all those folks who have recently begun their Cisco training.

This month we delivered new live classes on CCNA and CCNP. We are excited for and encourage our students at every level in their journey.   In that light, we have gathered a collection of Videos Answers, targeted at the CCNA level, with a few topics leaking into security and CCNP.   These videos were primarily created as quick (under 10 minutes each) Video Answers to questions that various learners have had.

Take a look at the list of topics, and if there are 1 or 2 you feel you would benefit from, feel free to enjoy them.

Here are a few of the topics (in no particular order):

• How the network statement really works in IOS
• Setting up SSH
• Initial commands for sanity sake
• Router on a stick

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One of community members found this great subnetting practice page. Enjoy!

Subnetting Practice Page

Some things never change. CCENT and CCNA candidates still have the roughest time in the curriculum with the topic of subnetting.

Hey! No problem! We have all been there. Just remain patient, remain calm, and keep working through examples and practice problems.

Do you want a quick quiz to see if your skills are up to speed? Check out this blog post:

Subnetting Practice Quiz 1

Let’s walkthrough a common subnetting question type in this blog entry. Here is the question, followed by how I would solve it in the written exam on my scratch paper.