IPv4 Subnetting

The Ultimate Guide

by Keith Barker

Total Videos : 16 Course Duration: 04:09:00
1. Course Intro (00:07:31)
2. Fun with IPv4 Basics (00:14:12)
3. Classes, Masks, and Private IPs (00:18:45)
4. Beautiful Binary (00:10:20)
5. Decimal to Binary Conversion (00:15:50)
6. The Mask Unveiled (00:13:00)
7. Stealing Host Bits (00:21:35)
8. Subnet IDs (00:20:06)
9. Valid Host Range (00:19:56)
10. Room for 1 More? (00:08:14)
11. Reverse Engineer (00:13:54)
12. Summarize (00:26:41)
13. Wildcard Masks (00:13:19)
14. Non-Octet Boundarys (00:16:04)
15. VLSM (00:15:29)
16. Final Exam (00:14:04)
This subnetting video training with Keith Barker covers subnetting with IPv4, including topics such as VLSM, Summarization, Wild Card Masks (for Cisco IOS), and more.

Related area of expertise:
  • Networking level 1

Recommended skills:
  • Students will benefit most from this course if they have completed Network+ training from CBT Nuggets or currently have 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

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

Course Intro

00:00:01 - Hello.
00:00:02 - My name is Keith Barker.
00:00:03 - And on behalf of the entire CBT Nuggets family, I'd like
00:00:06 - to welcome you to this course on IPv4 for subnetting.
00:00:10 - Let's begin.
00:00:11 - Let's start off by verifying that you and I are in exactly
00:00:15 - the right place at the right time by answering this
00:00:17 - question together.
00:00:18 - Who was this course created for?
00:00:20 - And in a word, it was created for you.
00:00:22 - For example, if you are working with any of these
00:00:25 - vendors right here, Cisco, Juniper, HP, PaloAlto,
00:00:28 - CheckPoint, or any other major player with networking gear,
00:00:31 - it is very likely that you're going to be working and
00:00:34 - dealing with IP addresses and subnets all of the time.
00:00:38 - A big challenge for people who are just coming into the world
00:00:41 - of networking and certification is that they get
00:00:43 - beat up, I mean big time beat up, by subnetting in those
00:00:47 - entry-level exams.
00:00:48 - Maybe up to 30% or 40% of an exam is surrounding IP
00:00:52 - addressing and subnetting of some type.
00:00:55 - So if you are a certification candidate, especially for the
00:00:58 - entry-level certification candidates, you absolutely
00:01:01 - want to make sure you take this course.
00:01:03 - If you're a network penetration tester, it's very
00:01:06 - important to understand subnets.
00:01:08 - For example, if you're a pen tester and you're doing an
00:01:10 - authorized scan of network devices, you may want to be
00:01:13 - familiar with how to calculate subnet ranges so you're
00:01:17 - setting your penetration testing on the right sections
00:01:20 - or summarizations of networks.
00:01:22 - And what I find a lot is there's end users who just
00:01:25 - want to know more about how IP addresses work in general.
00:01:29 - This is a perfect opportunity for you also to get that
00:01:32 - better understanding.
00:01:33 - Then one of my favorites that's near and dear to my
00:01:35 - heart is a manager who just wants to better understand
00:01:39 - what his technicians are talking about.
00:01:41 - So when the technician is talking about a slash 28 or a
00:01:44 - slash 25, the manager can have a really good understanding of
00:01:47 - what that technician is saying just by
00:01:49 - participating in this course.
00:01:51 - I also am going to add another one down here, and I'm going
00:01:53 - to put a line there.
00:01:54 - I'm going to get you fill in that one.
00:01:56 - It could be server administrators who are working
00:01:58 - with operating systems which are connected to networks,
00:02:01 - which are usually subnets.
00:02:03 - That would apply.
00:02:04 - And we could probably make several more.
00:02:05 - I'm going to ask you go ahead and in your mind fill in that
00:02:08 - last blank.
00:02:09 - Who also would benefit?
00:02:10 - And out of all of these items, it's very, very likely that
00:02:14 - you, my friend, are the prime candidate for this course.
00:02:18 - I am super excited to share the time with you.
00:02:20 - Let me give you a brief tour of what we're going to cover
00:02:22 - together in this course.
00:02:23 - We're going to start off with the basics of IPv4, the
00:02:26 - classes, the default masks, the private IP addresses.
00:02:29 - Taking a look at binary, because, after
00:02:31 - all is said and done--
00:02:32 - I'm going to share with you a boatload of shortcuts
00:02:34 - that you can use--
00:02:35 - we still absolutely deserve to understand what's really
00:02:38 - happening in binary behind the scenes, including the ability
00:02:42 - to convert on demand between decimal and binary and back.
00:02:46 - The importance of the mask, how we're stealing host bits
00:02:49 - to carve out custom subnets, identifying those subnets,
00:02:53 - identifying valid host ranges on each of those subnets.
00:02:56 - Making sure that you and I have enough host addressing
00:02:59 - space available on our new subnets for all the computers
00:03:02 - that need to be there.
00:03:03 - How do reverse engineer the process.
00:03:05 - For example, if we're given an IP address with a mask, how do
00:03:08 - we take that and then reverse engineer to determine very
00:03:11 - quickly what the actual subnet is that that customer is
00:03:15 - connected to?
00:03:16 - The process of summarization is also huge and very, very
00:03:19 - important, for example, with network statements or creating
00:03:22 - summary routes.
00:03:23 - We're going to using the techniques of summarization,
00:03:26 - so we're going to cover that in this course as well.
00:03:28 - And in a Cisco environment, wild card masks are also an
00:03:31 - important aspect of working with summarized or custom
00:03:35 - subnets, because they're needed inside of access lists
00:03:38 - and network statements if we're going to configure a
00:03:40 - Cisco IOS router correctly for custom subnetting.
00:03:44 - In non-octet boundaries, we'll take a look at how to start
00:03:46 - our custom subnetting somewhere in the middle, not
00:03:48 - on a clean octet boundary.
00:03:50 - And that's a really important precursor to doing the job of
00:03:53 - variable length subnet masking, where together we'll
00:03:56 - walk through, soup to dessert, the actual carving out of a
00:03:59 - variable length subnet masking plan.
00:04:01 - And at the end of that video, if you follow all these with
00:04:04 - me, you'll be able to do the exact same process.
00:04:07 - The cool thing is as we go through these videos together
00:04:10 - you'll be gaining these skills and improving your knowledge
00:04:13 - so that by the time we get to this last video called the
00:04:16 - final exam you'll have not only the knowledge of how to
00:04:19 - do something, you'll also have the measurable
00:04:21 - skills to do it.
00:04:22 - And that translates to taking those really awesome
00:04:24 - subnetting skills that you're going to gain and applying
00:04:27 - those to your networks that you deal with and manage on a
00:04:30 - daily basis.
00:04:31 - That's what gets me so excited about this course is because
00:04:33 - it's going to make a difference in your life as you
00:04:36 - work with IP subnets.
00:04:38 - Now I realize that we all come from different backgrounds and
00:04:41 - we're at different levels.
00:04:43 - So here's what I did for this course to optimize your time.
00:04:46 - I'd like you take all these videos in order, so video 1,
00:04:50 - 2, 3, 4, 5, all the way up to the very end.
00:04:54 - But here's the challenge.
00:04:55 - I know that some of you have some already pretty great
00:04:58 - subnetting skills.
00:04:59 - So if you're going through video 1 or 2, you may already
00:05:02 - have all the knowledge from that specific video.
00:05:05 - Here's what I did.
00:05:06 - In every single video, I've got an Opt Out
00:05:08 - section at the beginning.
00:05:10 - Here's how they work.
00:05:11 - At the beginning of each video, there's these Opt Out
00:05:14 - questions, and you simply read through them.
00:05:15 - If you know the correct answers to those questions,
00:05:18 - you can safely and comfortably skip that video.
00:05:22 - For example, if we take the Opt Out for video 2 and video
00:05:25 - 3, we look at video 4, and when we're looking at the
00:05:27 - questions we don't know the answers to them.
00:05:29 - We can then jump in right there and then continue our
00:05:32 - journey all the way to the end of the course.
00:05:35 - This is also very handy if you want to go back and review
00:05:38 - this course at some future time.
00:05:40 - By starting the video, looking at the Opt Out questions, you
00:05:43 - can very quickly assess whether or not you need to
00:05:45 - revisit the content in that video, or you can just go
00:05:48 - ahead and answer those questions and move forward.
00:05:50 - So we're taking absolute care to optimize your
00:05:53 - time in this course.
00:05:55 - Another question that I'd like you ask yourself is, how good
00:05:59 - do you want to be with IPv6 for subnetting?
00:06:02 - Perhaps you just want a casual understanding.
00:06:04 - So you can jump in the series, and then once we get up to
00:06:07 - variable length subnet masking and some advanced topics, you
00:06:11 - can go ahead and say, you know what?
00:06:11 - That's enough for me.
00:06:12 - I've had enough.
00:06:13 - But if you are the type of person who wants to be in the
00:06:16 - top 10% of people who understand how IP version 4
00:06:21 - subnetting works, I would strongly encourage you to take
00:06:24 - this course all the way from the beginning, go all the way
00:06:26 - to the end, and then review those pieces where you want to
00:06:29 - make sure you have those skills mastered.
00:06:32 - To that end, also in every single video I've embedded
00:06:35 - some expert exercises that I want you to do along with me.
00:06:39 - And as you participate with me in this course, that process
00:06:42 - of watch, learn, and conquer will become a reality as you
00:06:46 - master the skills of IPv4 subnetting.
00:06:50 - One of the reasons I'm so passionate and excited about
00:06:53 - this IPv4 something course is because this is the course I
00:06:57 - wish someone had created for me about two decades ago when
00:07:01 - I was first learning about IPv4.
00:07:04 - The great news is that this course is available to you.
00:07:07 - And I'm so excited about sharing this
00:07:09 - knowledge with you.
00:07:10 - Your action them right now is two basic things.
00:07:12 - Number one, I'd like you to grab a paper and something to
00:07:15 - write with.
00:07:16 - And then I'd like you to click Next to start the very next
00:07:19 - video as we begin with our basics of IP version 4.
00:07:23 - I am so excited about beginning this journey with
00:07:26 - you right now.
00:07:26 - I hope this has been informative for you, and I'd
00:07:29 - 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 Boundarys


Final Exam

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Keith Barker

Keith Barker

CBT Nuggets Trainer

Cisco CCIE Routing and Switching, Cisco CCIE Security, Cisco CCDP, HP-MASE, Brocade BCNP, (ISC)2 CISSSP, CompTIA’s Network+ and Security+, VMware VCP5-DCV, Palo Alto CNSE, Check Point CCSA

Area Of Expertise:
Cisco, security, networking, bitcoin. Author or coauthor of: CCNA Security 640-554 Official Cert Guide; CCNP Security IPS 642-627 Official Cert Guide; CCNA Security 640-554 Official Cert Guide, and many more.

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