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The Ultimate Guide

This real-world subnetting course with Keith Barker guides you through the step-by-step journey toward mastery of custom subnetting with IPv4. Topics include VLSM, Summarization, Wild Card Masks (for Cisco IOS), and more....
This real-world subnetting course with Keith Barker guides you through the step-by-step journey toward mastery of custom subnetting with IPv4. Topics include VLSM, Summarization, Wild Card Masks (for Cisco IOS), and more.

This training applies to real-world environments (vendor neutral), as well as all levels of certification from beginner through expert.

Recommended Experience
  • Students will benefit most from this course if they have completed CompTIA Network+ training from CBT Nuggets or currently have a basic understanding of network fundamentals.
Recommended Equipment
  • There is no equipment required in order to fully benefit from this course.
Related Certifications
  • This course does not map to a specific certification, but is applicable to a variety of certifications, particularly Cisco, Juniper, HP, Palo Alto, CheckPoint, Network+
Related Job Functions
  • Network Administrator
  • Network Engineer
  • Network Designer
Keith Barker has been a CBT Nuggets trainer since 2012 and holds a variety of networking and security certifications, including CCIE R&S, CCIE Security, (ISC)2 CISSP, Palo Alto CNSE, and VMware VCP5-DCV.
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1. Course Introduction (7 min)
2. Fun with IPv4 Basics (14 min)
3. Classes, Masks, and Private IPs (18 min)
4. Beautiful Binary (10 min)
5. Decimal to Binary Conversion (15 min)
6. The Mask Unveiled (13 min)
7. Stealing Host Bits (21 min)
8. Subnet IDs (20 min)
9. Valid Host Range (19 min)
10. Room for 1 More? (8 min)
11. Reverse Engineer (13 min)
12. Summarize (26 min)
13. Wildcard Masks (13 min)
14. Non-Octet Boundaries (16 min)
15. VLSM (15 min)
16. Final Exam (14 min)

Course Introduction


Hello. My name is Keith Barker. And on behalf of the entire CBT Nuggets family, I'd like to welcome you to this course on IPv4 for subnetting. Let's begin. Let's start off by verifying that you and I are in exactly the right place at the right time by answering this question together.


Who was this course created for? And in a word, it was created for you. For example, if you are working with any of these vendors right here, Cisco, Juniper, HP, PaloAlto, CheckPoint, or any other major player with networking gear, it is very likely that you're going to be working and dealing with IP addresses and subnets all of the time.


A big challenge for people who are just coming into the world of networking and certification is that they get beat up, I mean big time beat up, by subnetting in those entry-level exams. Maybe up to 30% or 40% of an exam is surrounding IP addressing and subnetting of some type.


So if you are a certification candidate, especially for the entry-level certification candidates, you absolutely want to make sure you take this course. If you're a network penetration tester, it's very important to understand subnets. For example, if you're a pen tester and you're doing an authorized scan of network devices, you may want to be familiar with how to calculate subnet ranges so you're setting your penetration testing on the right sections or summarizations of networks.


And what I find a lot is there's end users who just want to know more about how IP addresses work in general. This is a perfect opportunity for you also to get that better understanding. Then one of my favorites that's near and dear to my heart is a manager who just wants to better understand what his technicians are talking about.


So when the technician is talking about a slash 28 or a slash 25, the manager can have a really good understanding of what that technician is saying just by participating in this course. I also am going to add another one down here, and I'm going to put a line there.


I'm going to get you fill in that one. It could be server administrators who are working with operating systems which are connected to networks, which are usually subnets. That would apply. And we could probably make several more. I'm going to ask you go ahead and in your mind fill in that last blank.


Who also would benefit? And out of all of these items, it's very, very likely that you, my friend, are the prime candidate for this course. I am super excited to share the time with you. Let me give you a brief tour of what we're going to cover together in this course.


We're going to start off with the basics of IPv4, the classes, the default masks, the private IP addresses. Taking a look at binary, because, after all is said and done-- I'm going to share with you a boatload of shortcuts that you can use-- we still absolutely deserve to understand what's really happening in binary behind the scenes, including the ability to convert on demand between decimal and binary and back.


The importance of the mask, how we're stealing host bits to carve out custom subnets, identifying those subnets, identifying valid host ranges on each of those subnets. Making sure that you and I have enough host addressing space available on our new subnets for all the computers that need to be there.


How do reverse engineer the process. For example, if we're given an IP address with a mask, how do we take that and then reverse engineer to determine very quickly what the actual subnet is that that customer is connected to? The process of summarization is also huge and very, very important, for example, with network statements or creating summary routes.


We're going to using the techniques of summarization, so we're going to cover that in this course as well. And in a Cisco environment, wild card masks are also an important aspect of working with summarized or custom subnets, because they're needed inside of access lists and network statements if we're going to configure a Cisco IOS router correctly for custom subnetting.


In non-octet boundaries, we'll take a look at how to start our custom subnetting somewhere in the middle, not on a clean octet boundary. And that's a really important precursor to doing the job of variable length subnet masking, where together we'll walk through, soup to dessert, the actual carving out of a variable length subnet masking plan.


And at the end of that video, if you follow all these with me, you'll be able to do the exact same process. The cool thing is as we go through these videos together you'll be gaining these skills and improving your knowledge so that by the time we get to this last video called the final exam you'll have not only the knowledge of how to do something, you'll also have the measurable skills to do it.


And that translates to taking those really awesome subnetting skills that you're going to gain and applying those to your networks that you deal with and manage on a daily basis. That's what gets me so excited about this course is because it's going to make a difference in your life as you work with IP subnets.


Now I realize that we all come from different backgrounds and we're at different levels. So here's what I did for this course to optimize your time. I'd like you take all these videos in order, so video 1, 2, 3, 4, 5, all the way up to the very end. But here's the challenge.


I know that some of you have some already pretty great subnetting skills. So if you're going through video 1 or 2, you may already have all the knowledge from that specific video. Here's what I did. In every single video, I've got an Opt Out section at the beginning.


Here's how they work. At the beginning of each video, there's these Opt Out questions, and you simply read through them. If you know the correct answers to those questions, you can safely and comfortably skip that video. For example, if we take the Opt Out for video 2 and video 3, we look at video 4, and when we're looking at the questions we don't know the answers to them.


We can then jump in right there and then continue our journey all the way to the end of the course. This is also very handy if you want to go back and review this course at some future time. By starting the video, looking at the Opt Out questions, you can very quickly assess whether or not you need to revisit the content in that video, or you can just go ahead and answer those questions and move forward.


So we're taking absolute care to optimize your time in this course. Another question that I'd like you ask yourself is, how good do you want to be with IPv6 for subnetting? Perhaps you just want a casual understanding. So you can jump in the series, and then once we get up to variable length subnet masking and some advanced topics, you can go ahead and say, you know what?


That's enough for me. I've had enough. But if you are the type of person who wants to be in the top 10% of people who understand how IP version 4 subnetting works, I would strongly encourage you to take this course all the way from the beginning, go all the way to the end, and then review those pieces where you want to make sure you have those skills mastered.


To that end, also in every single video I've embedded some expert exercises that I want you to do along with me. And as you participate with me in this course, that process of watch, learn, and conquer will become a reality as you master the skills of IPv4 subnetting.


One of the reasons I'm so passionate and excited about this IPv4 something course is because this is the course I wish someone had created for me about two decades ago when I was first learning about IPv4. The great news is that this course is available to you.


And I'm so excited about sharing this knowledge with you. Your action them right now is two basic things. Number one, I'd like you to grab a paper and something to write with. And then I'd like you to click Next to start the very next video as we begin with our basics of IP version 4.


I am so excited about beginning this journey with you right now. I hope this has been informative for you, and I'd like to thank you for viewing.

Fun with IPv4 Basics

Classes, Masks, and Private IPs

Beautiful Binary

Decimal to Binary Conversion

The Mask Unveiled

Stealing Host Bits

Subnet IDs

Valid Host Range

Room for 1 More?

Reverse Engineer


Wildcard Masks

Non-Octet Boundaries


Final Exam

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Entry 4 hrs 16 videos


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Keith Barker
Nugget trainer since 2012