CCNA Crash Course Student QA Post

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CCNA Crash Course - Q&A Post

I teach a CCNA course on O’Reilly Online titled “CCNA Crash Course”. During the multi-day course, if students have questions, they can come here to ask follow-up questions. Simple enough.

Note: When you add your first few comments here the anti-spam features do not allow your post to display until I manually approve it. So please be patient. When the course is active I plan to check multiple times during business hours in US Eastern Time (UTC-5).

About the CCNA Crash Course

O’Reilly Online Learning offers a large variety of books, videos, labs, and live learning events. I’ve been teaching there since 2019, and in 2022 I began teaching the CCNA Crash Course at their site. The CCNA Crash Course sets about to help you learn as much of the CCNA content as possible within the 16 hours of the live course, with a study plan for other activities to do outside the course.

The blog post you came across today happens to be specifically for the CCNA Crash Course scheduled for Feb 7, 8, 14, 15 in the year 2022. You’re welcome to join the course! If you do not yet have a subscription to O’Reilly, if you time it right, you might be able to attend the whole course during an O’Reilly trial period as well.

For future classes, you can try this link, which shows all of the classes I’m scheduled to teach. Or just go to and search.

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Hello, I’m not sure where to ask this but in your CCNA 200-301 Volume 1 book, Chapter 9 Figures 9-5 and 9-6. You say G0/1 from SW3 had a cost of 5. I’m stuck on this part trying to figure out why? Am I missing something?

Wendell Odom

Hi Dakota,
Yeah, I think you’re restricting your thinking to default port costs only. The port cost can be configured to a positive integer. In that example, there’s one interface that uses a non-default value.


Hello, in ccna book 2 ch.11 Q.3 in the Diffserv question the answers don’t seem to be given in the ‘Classification and Marking’ section. Am I correct or just not reading it properly?

Wendell Odom

Hi Chris,
My first reaction was “maybe”. Keeping track of what minutia is included in specific editions of books, and ensuring the Q/A is answerable, takes a lot of work – and sometimes we make mistakes. In this case, I think it’s all covered.

First, for future readers… we’re discussing the CCNA 200-301 Official Cert Guide, Volume 2, published late 2019. Chapter 11, about QoS.

Look at the material just before Figure 11-4, and following for about 3 pages for the related content. EG, under heading “Classification on Routers with ACLs and NBAR” discusses a couple of the answers. Admittedly, the discussion of matching (aka classifying) based on DSCP is brief, just before Figure 11-4, and maybe alluded to in later examples. That might be an expert blindspot that you revealed, where I assumed it was obvious (but it wouldn’t necessarily be for someone new to the topic.) Feel free to let me know if that’s what you found confusing.

Hope this helps!!

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