Overview

In this short blog post we are going to present a simple procedure for IPv4 prefix summarization. The procedure is based on the one found in “Optimal Routing Design” book by Russ White, Don Slice and Alvaro Retana, but differs in some respects. The process is three step, and require the use of Windows calculator for ease of computation. No binary breakdowns are involved, just some basic arithmetic. For the sake of simplicity, we skip all proofs, as those are trivial. The same approach could be adopted for use with IPv6 prefixes, provided that decimal arithmetic is replaced with hexadecimal.

Scenario

We are going to use an example to demonstrate the method. Here is the task: find the optimal (longest prefix length) summary prefix for the following set of subnets:

192.168.100.0/22
192.168.101.0/24
192.168.99.0/24
192.168.102.0/24
192.168.105.0/24
192.168.98.0/23

This example is taken from the wikipedia article: http://en.wikipedia.org/wiki/Supernet that illustrates the use of binary breakdown for the purpose of address summarization.
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It was a dark, cold night in late December, and Bob, (the optimistic firewall technician), had a single ASA to deploy before going home for the holidays.  The requirements for the firewall were simple.   Bob read them slowly as follows:

1. R1 should be able to ping the server “Radio.INE.com” by name.
2. PC should be able to ping the server “Radio.INE.com” by name.

Bob also read the background information to see if this was something he could finish before leaving the office.   Bob read the following:

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Hello everyone! We want your feedback on changes to this product sent to: asequeira@ine.com

Here is what we are going to do for sure:

1. Replace rote memorization questions with newer, more accurate questions for the actual Core Knowledge Section.

Here is what we are proposing or at least thinking about :

1. Eliminate all computer grading and move to self-graded questions.
2. Organize questions by topic area of the blueprint.

We look forward to your feedback on these proposed changes – or anything else you want done.

Happy studying everyone!

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.

“You run the ipconfig command and discover your IP address and subnet mask are: 172.16.129.180/255.255.255.128. What is your network address?”

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The Beta Test is over! Check out W-INE Radio at:

http://radio.ine.com:8000/listen.m3u

The station features Tech Talks and other fun, educational sessions, as well as CD quality tunes to study by!

The Podcast of our Core Knowledge Section Tech Talk is available at:

http://www.ine.com/podcasts/ckp1.mp3

Do you have programming suggestions? Just e-mail wineradio@ine.com

I hear the question in Live Bootcamps, and I see it on our forums all the time -  What kind of questions can I expect to come across in the Core Knowledge section of the Lab Exam, and how should I answer them?

Here are some examples of the various question types I believe you can encounter, and my sample responses. I also provide some tips on surviving these buggers.

Question Type 1 – Memorization Type Questions

Q: Your Cisco router has learned a prefix from RIP version 2 and ODR. Which will your router prefer and why?

A: Your Cisco router will prefer the route from RIP version 2 as it possesses the preferable Administrative Distance.

Tip: For questions like this, we need to get back to basics and do some good old fashioned memorization. I suggest making Flash Cards for potential questions of this nature.

Question Type 2 – “Trick” Questions

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Two new Hands On Labs are being added to the course this weekend. Enjoy!

• Configuring a Back-to-Back Serial WAN Connection
• Configuring a Back-to-Back PPP WAN Connection

Yet another Practice Exam will be added this weekend to the CCENT course for our students to enjoy. Make sure you are ready for the actual exam by challenging yourself with the latest, and toughest exam simulation!

We are adding practices for common commands you need to know to the CCENT course. We uploaded an updated Verifying the WAN Connection lesson tonight. Want to experience a sample practice right now? Use the link below. Happy studies!

Verifying the WAN Connection