Acing the CCNA Exam, Volume 1: Fundamentals and Protocols

Acing the CCNA Exam

Volume 1

Fundamentals and Protocols

Jeremy McDowell

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contents

Front matter

preface

acknowledgments

about this book

about the author

about the cover illustration

  1   Introduction to the CCNA

  1.1   What is the CCNA?

The six domains of the CCNA exam

Format of the CCNA Exam

Scheduling and taking the exam

  1.2   Why get CCNA-certified?

  1.3   The structure of this book

  1.4   How to study for the CCNA

Using a book

Using a video course

Lab exercises

Using multiple resources together

Part 1.  Network fundamentals

  2   Network devices

  2.1   What is a network?

  2.2   Types of network devices

Clients and servers

Switches

Routers

Firewalls

  3   Cables, connectors, and ports

  3.1   Network standards

  3.2   Binary: Bits and bytes

  3.3   Copper UTP connections

IEEE 802.3 standards (copper)

Straight-through and crossover cables

  3.4   Fiber-optic connections

The anatomy of a fiber-optic cable

UTP vs. fiber

  4   The TCP/IP networking model

  4.1   Conceptual models of networking

  4.2   The OSI reference model

  4.3   The TCP/IP model

The layers of the TCP/IP model

Data encapsulation and de-encapsulation

  5   The Cisco IOS CLI

  5.1   Shells: GUI and CLI

GUI and CLI

Accessing the CLI of a Cisco device

  5.2   Navigating the Cisco IOS CLI

The EXEC modes

Global configuration mode

Keyboard shortcuts

Context-sensitive help

  5.3   IOS configuration files

  5.4   Password-protecting privileged EXEC mode

Configuring the enable password

Configuring the enable secret

  6   Ethernet LAN switching

  6.1   Local area networks

  6.2   The Ethernet header and trailer

Preamble and SFD

Destination and source

Type/Length

Frame Check Sequence

  6.3   Frame switching

MAC address learning

Frame flooding and forwarding

The MAC address table in Cisco IOS

  6.4   Address Resolution Protocol

  6.5   Ping

  7   IPv4 addressing

  7.1   The IPv4 header

The Version field

The IHL field

The DSCP and ECN fields

The Total Length field

The Identification, Flags, and Fragment Offset fields

The TTL field

The Protocol field

The Header Checksum field

The Source Address and Destination Address fields

The Options field

  7.2   The binary number system

Decimal

Binary

  7.3   IPv4 addressing

The structure of an IPv4 address

Configuring IPv4 addresses on a router

Attributes of an IPv4 network

IPv4 address classes

  8   Router and switch interfaces

  8.1   Configuring interfaces

Interface descriptions

Interface speed

Interface duplex

  8.2   Autonegotiation

  8.3   Interface errors

Speed mismatches

Duplex mismatches

Part 2.  Routing fundamentals and subnetting

  9   Routing fundamentals

  9.1   How end hosts send packets

  9.2   The basics of routing

The routing table

Route selection

  9.3   Static routing

Configuring static routes

Configuring a default route

10   The life of a packet

10.1   The life of a packet from PC1 to PC3

PC1 to R1

R1 to R2

R2 to R3

R3 to PC3

10.2   The life of a packet from PC3 to PC1

11   Subnetting IPv4 networks

11.1   What is subnetting?

11.2   FLSM subnetting

Subnetting /24 address blocks

Subnetting /16 address blocks

Subnetting /8 address blocks

FLSM scenarios

11.3   VLSM subnetting

Assigning Toronto LAN A’s subnet

Assigning Tokyo LAN A’s subnet

Assigning Toronto LAN B’s subnet

Assigning Tokyo LAN B’s subnet

Assigning the WAN connection’s subnet

11.4   Additional subnetting practice

Part 3.  Layer 2 concepts

12   VLANs

12.1   Why we need VLANs

Layer 3 segmentation with subnets

Layer 2 segmentation with VLANs

12.2   Configuring VLANs and access ports

Creating and naming VLANs

Assigning ports to VLANs

12.3   Connecting switches with trunk ports

The IEEE 802.1Q tag

Configuring trunk ports

12.4   Inter-VLAN routing

Router on a stick

Multilayer switching

13   Dynamic Trunking Protocol and VLAN Trunking Protocol

13.1   Dynamic Trunking Protocol

DTP negotiation

Disabling DTP

13.2   VLAN Trunking Protocol

VTP synchronization

VTP modes

VTP versions

Is VTP dangerous?

14   Spanning Tree Protocol

14.1   The need for STP

14.2   How STP works

14.3   The STP algorithm

Root bridge election

Root port selection

Designated port selection

14.4   STP port states and timers

STP port states

STP timers

14.5   PortFast and BPDU Guard

PortFast

BPDU Guard

15   Rapid Spanning Tree Protocol

15.1   Spanning Tree Protocol versions

15.2   STP and RSTP comparison

Port costs

Port states

Port roles

RSTP topology changes

15.3   RSTP link types

15.4   Root Guard, Loop Guard, and BPDU Filter

Root Guard

Loop Guard

BPDU Filter

16   EtherChannel

16.1   How EtherChannel works

16.2   EtherChannel configuration

Dynamic EtherChannel

Static EtherChannel

Physical port configurations

16.3   EtherChannel load balancing

16.4   Layer 3 EtherChannel

Part 4.  Dynamic routing and first hop redundancy protocols

17   Dynamic routing

17.1   Dynamic routing vs. static routing

Adaptability

Scalability

17.2   Types of routing protocols

Interior gateway protocols

Exterior gateway protocols

17.3   Route selection

The metric parameter

The administrative distance parameter

Route selection examples

17.4   The network command

18   Open Shortest Path First

18.1   OSPF foundations

The link-state database

OSPF areas

OSPF cost

18.2   OSPF configuration

The router ID

Activating OSPF on interfaces

Passive interfaces

Advertising a default route

18.3   Neighbors and adjacencies

Neighbor states

OSPF network types

Neighbor requirements

18.4   LSA types

19   First hop redundancy protocols

19.1   FHRP concepts

Providing a redundant default gateway

FHRP neighbor relationships

Failover

19.2   Comparing FHRPs

Hot Standby Router Protocol

Virtual Router Redundancy Protocol

Gateway Load Balancing Protocol

19.3   Basic HSRP configuration

Part 5.  IPv6

20   IPv6 addressing

20.1   The need for IPv6

20.2   Hexadecimal

20.3   IPv6 addressing

IPv6 header

IPv6 address structure

Abbreviating IPv6 addresses

Identifying the IPv6 prefix

20.4   IPv6 address configuration

Manually assigning an IPv6 address

Modified EUI-64

20.5   IPv6 address types

Global unicast

Unique local

Link-local

Multicast

Anycast addresses

Other reserved addresses

21   IPv6 routing

21.1   Neighbor Discovery Protocol

Solicited-node multicast

Address resolution with NDP

Router discovery with NDP

Duplicate Address Detection

21.2   The IPv6 routing table

Connected and local routes

Route selection

21.3   IPv6 static routing

Configuring IPv6 static routes

Link-local next hops

Configuring a default route

Floating static routes

Part 6.  Layer 4 and IP access control lists

22   Transmission Control Protocol and User Datagram Protocol

22.1   The role of Layer 4

Port numbers

Session multiplexing

22.2   TCP and UDP

Transmission Control Protocol

User Datagram Protocol

Comparing TCP and UDP

23   Standard access control lists

23.1   How ACLs work

Matching and acting on packets

The implicit deny

Applying ACLs

ACL types

23.2   Configuring standard ACLs

Numbered ACLs

Named ACLs

23.3   Example scenario

24   Extended access control lists

24.1   Configuring extended ACLs

Matching protocol, source, and destination

Matching TCP/UDP port numbers

24.2   Example security requirements

24.3   Editing ACLs

Deleting ACEs

Resequencing ACEs

Appendix A.   Exam topics reference table

Appendix B.   CLI command reference table

Appendix C.   Chapter quiz questions

Appendix D.   Chapter quiz answers

index

front matter

preface

In 2018, as a junior high school English teacher in the city of Kobe, Japan, I found myself at a crossroads. What I had originally intended to be a brief teaching stint in Japan had stretched into four years, and I was reaching the limit of my stay. I was in Japan on the Japan Exchange and Teaching (JET) Programme, a program sponsored by the Japanese government to bring recent university graduates to Japan to teach English for up to 5 years. As my tenure neared its end, I pondered my next step.

Being fascinated with computers since childhood, I found the field of IT a natural choice. I was no computer wizard—I had no experience in programming or anything of the sort—but after some searching, I stumbled upon the Cisco Certified Network Associate (CCNA) certification. If the stories were to be believed, getting CCNA certified was the gateway to a promising career in IT with a decent salary and plenty of room for growth. After a bit of studying, I was hooked! Peering under the hood of networks like the internet—an ubiquitous part of the modern world—was (and still is) endlessly fascinating.

Fast forward a year to 2019, and I was a network engineer at the world’s leading colocation data center and interconnection provider! I share my personal story here to emphasize that, with no formal education or previous experience on the topic, I was able to self-study, get certified, and make a 180-degree career change to enter the IT industry. And my story is no exception; I hear such stories from students all over the world on a daily basis.

You will occasionally encounter naysayers who downplay the value of the CCNA these days. One common argument is that, with the rise of cloud services like Amazon Web Services (AWS) and Microsoft Azure, there is less demand for network engineers; students should pursue cloud providers’ certifications instead. I couldn’t disagree more; connecting the complex multicloud infrastructure used by many modern enterprises is no simple task, and we need network professionals more than ever. 

Studying a particular cloud service provider’s solutions before learning the fundamentals of networking is simply putting the cart before the horse—a house built on sand. The same can be said of pursuing the field of cybersecurity before grasping basics like networking. Network fundamentals are foundational knowledge for any IT professional, and the CCNA exam tests and certifies not only that you understand the fundamentals, but also that you have the skills to apply them in real networks. In our increasingly interconnected world, such knowledge and skills are invaluable—my story, and countless others’ stories, prove that.

This book—consisting of two volumes—is the culmination of insights gained from countless interactions with many thousands of students of my CCNA video course, refined and expanded to offer a comprehensive resource. For countless people—including myself—becoming CCNA certified has been truly life changing. There will be struggles and setbacks, but if you’re looking to make a change in your life and career, I can’t recommend the CCNA enough, and I hope that this book will inspire and empower you to pursue and achieve your CCNA certification.

acknowledgments

Writing and publishing a book is a major undertaking—certainly not something I could have done on my own! I’d like to thank everyone who contributed to this book in one way or another, directly or indirectly.

Thank you, to everyone at Manning who has worked hard on this book; there is a lot of behind-the-scenes work that goes into publishing a book. I’d like to thank my editor Connor O’Brien most of all for his valuable feedback on each chapter of this book. The book has turned out far better than it ever could have without his detailed reviews and guidance.

Thank you, Andy Waldron, acquisitions editor at Manning, for giving me a chance to write this book. I reached out to a few publishers about writing a CCNA book, and Andy was quick to respond and express his interest. After a few quick calls, the contract was signed, and the rest is history!

Thank you, Jeremy Cioara, for your contributions as technical editor for the book. Jeremy Cioara is an author, educator, and business owner known for his ability to simplify complex technical concepts into entertaining and practical explanations. He brings more than two decades of experience, a love of learning, and a keen eye for detail.

Thank you, all of the reviewers, for your time and valuable feedback at each stage of the process: Amit Lamba, Andrea Cosentino, Casey Burnett, Eder Andrés Ávila Niño, Emmanuele Piccinelli, Emilio Grande, Gavin Smith, George Gyftogiannis, Glen Thompson, Greg MacLean, Jeremy Chen, John Bisgrove, John Guthrie, Jose Apablaza, Narayanan Seshan, Nghia To, Paul Love, Pedro Seromenho, Raghunath Mysore, Simone Sguazza, Sushil Singh, Vladislav Bilay, and Zachary Manning. Special thanks go to Munish Kaushal, my technical proofreader, for your careful reviews of the many (very many!) figures, commands, and examples in this book.

I’d also like to thank everyone who has supported Jeremy’s IT Lab during the past five years. It’s because of all of you that I can pursue my dream as a job—for that, I am forever grateful. Writing a CCNA book would never have crossed my mind without your support. Special thanks go to those on the Jeremy’s IT Lab Discord server for being a totally awesome and supportive group, always willing to lend a hand and lift each other up (without forgetting to have fun).

Finally, thank you, my friends and family who have supported me in my personal life during this process; writing a book is a major time commitment and often means neglecting the more important parts of life. Thank you, Miki, for your understanding and constant encouragement during my long work hours throughout the whole process, and thanks, Mom and Dad, for your support and encouragement as always.

about this book

Acing the CCNA Exam was written with one goal in mind: to help you prepare for and successfully pass the CCNA exam. It begins from zero and assumes no previous knowledge, covering network fundamentals and every CCNA exam topic step by step. 

Who should read this book

As an exam study guide, this book is for anyone who wants to pass the CCNA exam and attain their CCNA certification. If that’s you (good choice, by the way), you’ve come to the right place! Even for those who already have their CCNA or are already working in the field, this book will be a useful resource for reference, covering key network protocols and how to configure them on Cisco routers and switches.

How this book is organized

The CCNA exam is quite wide in scope, and as a result, this book is divided into two volumes. This is volume 1, consisting of 24 chapters arranged across 6 parts:

Chapter 1, separate from the main 6 parts, serves as an introduction to the CCNA exam: what it is, why you should get CCNA certified, and advice about how to study for the exam.

Part 1 lays the foundation of networking concepts, introducing how networks operate at a basic level, the devices that form a network, and the protocols that govern communication:

Chapter 2 introduces some of the different types of devices, such as routers and switches, that make up networks, and the roles of each.

Chapter 3 covers the different cables, connectors, and ports that are used to physically connect devices to form a network.

Chapter 4 covers the TCP/IP model, a network blueprint that conceptualizes the various functions involved in network communications.

Chapter 5 introduces the command-line interface (CLI) of Cisco routers and switches—the text-based interface that we will use to interact with and configure them throughout this book.

Chapter 6 focuses on the role of Ethernet switches in facilitating communications within a local area network (LAN).

Chapter 7 covers Internet Protocol version 4 (IPv4) addresses; these are how computers identify each other on a network.

Chapter 8 focuses on the interfaces that connect Cisco routers and switches and how to configure them.

Part 2 delves into how data navigates through complex networks, focusing on routing principles, the end-to-end journey of a data packet, and segmenting a network with subnetting:

Chapter 9 covers the fundamentals of routing—the process by which routers forward packets to destinations in remote networks.

Chapter 10 is a deep dive into the various processes involved in delivering a message from one host to another, reviewing the key concepts covered up to this point.

Chapter 11 introduces subnetting, which is the process of dividing a larger IP network into multiple smaller networks.

Part 3 focuses on technologies and protocols used by switches to facilitate their role in forwarding frames in an efficient, reliable, and secure manner:

Chapter 12 covers virtual LANs (VLANs), which are used to segment a LAN for improved efficiency and security.

Chapter 13 explains Dynamic Trunking Protocol (DTP) and VLAN Trunking Protocol (VTP), which play key roles in the configuration and management of VLANs.

Chapter 14 introduces Spanning Tree Protocol (STP), a protocol that ensures a loop-free topology in Ethernet LANs.

Chapter 15 delves into Rapid Spanning Tree Protocol (RSTP), an evolution of STP that provides faster convergence.

Chapter 16 discusses EtherChannel, a technology that combines multiple physical links into a single logical unit to increase bandwidth while providing redundancy.

Part 4 covers key protocols used by routers—dynamic routing protocols to enable automatic and adaptive packet forwarding, and first-hop redundancy protocols to provide a reliable gateway for hosts in a LAN:

Chapter 17 introduces dynamic routing, focusing on the various protocols that enable routers to communicate with each other and dynamically build their routing tables.

Chapter 18 focuses on Open Shortest Path First (OSPF), the most common dynamic routing protocol used by routers within an organization.

Chapter 19 explains first hop redundancy protocols (FHRPs), which provide continuous network availability by allowing routers to coordinate and provide a redundant default gateway.

Part 5 introduces the next generation of the Internet Protocol, IPv6, designed to overcome the limitations of IPv4 and support the internet of the future:

Chapter 20 covers IPv6 addressing, detailing the structure and various types of IPv6 addresses.

Chapter 21 delves into familiar routing concepts from an IPv6 perspective, focusing on configuring IPv6 static routes.

Part 6 explores the role of the Layer 4 protocols TCP and UDP, as well as how to use IP access controls lists (ACLs) for filtering and securing network traffic:

Chapter 22 discusses Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), the core protocols of the Transport Layer.

Chapter 23 introduces standard ACLs, which identify and filter packets based on their source IP address.

Chapter 24 covers extended ACLs, which provide more granular traffic filtering based on IP addresses, port numbers, and protocol types.

Additionally, there are four appendixes, each of which should prove helpful in your exam preparation:

Appendix A is a reference table that lists the CCNA exam topics and which chapters of each volume cover each topic.

Appendix B is a reference table that lists the Cisco IOS CLI commands covered in each chapter of this volume, with a brief description of each.

Appendix C consists of several quiz questions for each chapter of this volume. I recommend using these questions to test your understanding after studying each chapter, and then doing the same for review as necessary.

Appendix D lists the correct answers to the chapter quiz questions in appendix C and gives a brief explanation for each answer.

If you are just beginning your CCNA studies, I highly recommend starting from volume 1 (this volume) and reading the chapters in order; each chapter builds upon the previous ones, assuming familiarity with all preceding material. However, if you are using this book as a secondary resource (having already completed another course of study, such as my video series), feel free to treat the book more as a reference guide. In this case, you can directly consult chapters that address specific areas you want to focus on. Appendix A will be particularly useful for this targeted study, as it lists which chapters in which volume address each CCNA exam topic.

About Cisco CLI commands and output formatting

This book contains many examples of Cisco command-line interface (CLI) commands and output in examples and in line with normal text. These examples are formatted in a fixed-width font like this to separate it from ordinary text, using the syntax conventions shown in the following table. Code annotations accompany many of the code examples and highlight important concepts. Where necessary, the code has been reformatted to accommodate the available page space, and where code wraps, we've used line-continuation markers (➥).

Table 1 CLI syntax conventions

Each command in this book will be explained as it is introduced, but you can refer to this table as needed for clarification. The following examples demonstrate some of these different syntax conventions:

show ip interface[interface]

You must type show ip interface and then optionally provide a value for the interface argument.

vtp version {1 | 2 | 3}

You must type vtp mode and then the keyword 1, 2, or 3.

switchport trunk allowed vlan [add | remove | except] vlans

You must type switchport trunk allowed vlan, optionally specify one of the listed keywords, and then specify a value for the vlans argument.

R1(config-if)# interface g0/1

The command prompt R1(config-if)# was displayed, and the user typed the command interface g0/1.

liveBook discussion forum

Purchase of Acing the CCNA Exam includes free access to liveBook, Manning’s online reading platform. Using liveBook’s exclusive discussion features, you can attach comments to the book globally or to specific sections or paragraphs. It’s a snap to make notes for yourself, ask and answer technical questions, and receive help from the author and other users. To access the forum, go to https://livebook.manning.com/book/acing-the-ccna-exam-fundamentals-and-protocols/discussion. You can also learn more about Manning’s forums and the rules of conduct at https://livebook.manning.com/discussion.

Manning’s commitment to our readers is to provide a venue where a meaningful dialogue between individual readers and between readers and the author can take place. It is not a commitment to any specific amount of participation on the part of the author, whose contribution to the forum remains voluntary (and unpaid). We suggest you try asking him some challenging questions lest his interest stray! The forum and the archives of previous discussions will be accessible from the publisher’s website as long as the book is in print.

Other online resources

There is no shortage of helpful resources for CCNA students online. I have collected some of my recommended resources (video courses, practice exams, etc.) on my website at https://www.jeremysitlab.com/ccna-resources.

Another page that every CCNA candidate should have bookmarked is the official exam topics list at https://learningnetwork.cisco.com/s/ccna-exam-topics. This is where you can find what Cisco expects you to know to pass the CCNA exam. 

Finally, I recommend bookmarking Cisco Certification Roadmaps at https://learningnetwork.cisco.com/s/cisco-certification-roadmaps. This page will give you information about Cisco’s yearly certification review process. If there are any scheduled changes coming to the CCNA exam, they will be listed on this page well in advance.

about the author

Jeremy McDowell

is a senior network engineer from Canada, living and working in Japan for over 10 years. After graduating with a bachelor of music degree from the University of Toronto, he taught English in Japan for five years before entering the networking industry in 2019.

Combining his knowledge of networking with his teaching skills, Jeremy has helped thousands of students study for and pass the CCNA exam through his YouTube channel Jeremy’s IT Lab, which currently has over 340,000 subscribers.

about the cover illustration

The figure on the cover of Acing the CCNA Exam, titled Maître d’école, or Teacher, is taken from a book by Louis Curmer published in 1841. Each illustration is finely drawn and colored by hand.

In those days, it was easy to identify where people lived and what their trade or station in life was just by their dress. Manning celebrates the inventiveness and initiative of the computer business with book covers based on the rich diversity of regional culture centuries ago, brought back to life by pictures from collections such as this one.

1 Introduction to the CCNA

This chapter covers

What is the CCNA?

Why study for the CCNA?

How to study for the CCNA

In this chapter, we will take a look at the CCNA exam itself, why it’s valuable, and how you should go about studying for it. If you are interested enough in the CCNA to buy a book about it, chances are you already have a basic idea about what the CCNA is. You also certainly have your own reasons for wanting to study for the CCNA. However, I hope this chapter helps clarify some doubts you may have and encourages you to continue down the path to achieving the CCNA certification.

1.1 What is the CCNA?

The Cisco Certified Network Associate (CCNA) is an entry-level networking certification by Cisco Systems, and it is also the name of the exam you have to pass to become CCNA certified. The CCNA exam tests a candidate on various aspects of networking, such as IP addressing, wired and wireless network connections, routing and switching packets across a network, network services, security fundamentals, network automation, and many more. The various topics of the CCNA exam are organized into six logical domains.

1.1.1 The six domains of the CCNA exam

The six domains tested on the CCNA exam and their relative weightings are as follows:

1.0 Network Fundamentals—20%

2.0 Network Access—20%

3.0 IP Connectivity—25%

4.0 IP Services—10%

5.0 Security Fundamentals—15%

6.0 Automation and Programmability—10%

Within each of the domains, there are various topics and subtopics. If you are planning to take the CCNA exam, it is a good idea to know exactly what Cisco expects of you. Fortunately, Cisco has you covered; you can view the CCNA exam topics list on the Cisco Learning Network at http://mng.bz/AdVx.

Looking at the list of exam topics at the start of your studies might be a bit intimidating. If you are like I was when I started studying for the CCNA in 2018, you might have heard of an IP address before, but everything else on that list seems like a foreign language. Rest assured that if you follow volumes 1 and 2 of this book from start to end and take your time to understand the concepts, you will be fluent in the language of networking. You won’t be an expert, but you will have the foundational knowledge and skills necessary to take on the CCNA exam and enter the world of network professionals.

I have heard the CCNA described as a mile wide and an inch deep. Objectively speaking, that statement is true. The CCNA covers a wide variety of topics related to the field of networking, and as an entry-level certification, it does not dig deep into many nitty-gritty details, especially compared to Cisco’s higher-level certifications like Cisco Certified Network Professional (CCNP) and Cisco Certified Internetwork Expert (CCIE). However, do not let this statement make you underestimate the CCNA or think it is trivial. It is often more difficult to wrap your head around a topic for the first time than it is to dig deeper once you already have a grasp of the fundamentals, and the CCNA certainly includes plenty of new topics for an aspiring engineer to understand. The CCNA is also much more comprehensive and challenging than comparable entry-level networking certifications like CompTIA’s Network+.

Although the CCNA is a vendor-specific certification (as opposed to a vendor-neutral certification like Network+), it is the de facto industry standard entry-level certification in the networking industry. In addition to testing your skills at configuring and troubleshooting Cisco routers and switches, the CCNA tests your knowledge of the fundamentals of networking. Modern networks use a variety of standard protocols that apply regardless of which vendor’s device is running them. IP (Internet Protocol) is IP; it does not matter whether it is being used by a Cisco router, an Apple iPhone, or a Windows PC. The CCNA requires a combination of theoretical knowledge of standard protocols, as well as practical application on Cisco devices. That makes it one of the most respected and desired entry-level certifications not just for network professionals but also for IT professionals in general.

1.1.2 Format of the CCNA Exam

The CCNA is a 120-minute exam covering the six exam topic domains previously listed. The majority of the questions are multiple choice, but you can expect questions of various formats, such as

Multiple choice, single answer—The question won’t state select one, but you’ll only be able to select one option at a time.

Multiple choice, multiple answers—The question will clearly indicate how many options to select: select two, select three, etc.

Drag and drop—In these questions, you are required to move items or options from one part of the screen to another to correctly answer the question. This can involve matching terms with definitions, sequencing steps in a process, etc.

Lab simulations—In these questions, you will log in to and configure Cisco routers and switches in a simulated network.

Cisco has a short video summarizing each of the four question types. I recommend taking a look to familiarize yourself with the question types and the exam interface: http://mng.bz/ZEpA.

When taking the CCNA exam, questions are randomly selected from a large pool, so no two test-takers will have the exact same experience. This applies to both the types and order of questions, as well as their distribution across the six exam domains. Although the exam topics list is divided into six sections, the exam itself is not. You will receive a set number of questions and have 120 minutes to answer them, managing your time as needed. And here’s an important point: after you answer or skip a question, you can’t go back! Don’t make the mistake of skipping a difficult question with the intention of answering it later—this is not possible.

Exam tip Effective time management is crucial for success on the CCNA exam. Some questions, particularly lab simulations, demand more time than others, so it’s important to allocate sufficient time for these questions. The challenge lies in not knowing the exact number of lab simulation questions or their placement within the exam. For example, if you only have 1 minute left and the final question is a lab simulation, it’s unlikely you’ll be able to finish the question, resulting in lost points. My recommendation is to answer the more straightforward questions confidently and move on—avoid spending excessive time second-guessing yourself. If you don’t know the answer, select one and move on—there is no penalty for guessing.

Cisco keeps the exact contents of the exam and the grading scheme tightly protected, but the general consensus is that the lab simulations are more heavily weighted than the other question types. There’s a study tip: when studying for the CCNA, never skip the lab exercises! Whether the lab simulations on the exam are more heavily weighted or not, hands-on practice is still essential for studying.

Exam scenarios

Throughout the book, you will find several exam scenarios that present questions similar to what you might find on the CCNA exam. Note that these aren’t actual CCNA exam questions. The contents of Cisco’s exams are protected by a nondisclosure agreement (NDA) that you must accept before taking each exam. Violating the NDA will result in Cisco banning you from their certification program. This includes accessing leaked exam questions to prepare for an exam; don’t do it!

1.1.3 Scheduling and taking the exam

The CCNA exam, administered by Cisco’s testing partner Pearson VUE, can be taken either at an authorized test center or online. To schedule the exam, visit CertMetrics (https://cp.certmetrics.com/cisco/en/login). If you don’t have a Cisco account yet, you’ll have to make one; just click Sign Up, and make an account.

Once logged in to CertMetrics, click Schedule Now to proceed to the Pearson VUE website, where you can find the CCNA exam under Proctored Exams. Here, you can choose between taking the exam at a test center or online.

Some prefer to schedule the exam at the start of their studies and build a study plan based on that date. However, if this is your first time taking a certification exam, I advise against this, as the time required for preparation can vary depending on factors like your work and educational background and the amount of time you can dedicate to studying.

Note The CCNA is not held on specific dates; you are free to schedule and take the exam at any time throughout the year. Online exams are available 24/7 (depending on the availability of proctors), but in-person exams depend on the test center’s availability.

Both test center and online exams are proctored to ensure exam integrity. At a test center, staff will be present to monitor you. If you take the exam online, a proctor will confirm that you have a suitable testing environment before the exam (possibly asking you to remove objects around your desk or walls) and monitor you via webcam and microphone during the exam. For details about online testing, check out Cisco’s page here: http://mng.bz/RZvv. If you can’t secure a quiet, private location for at least 2 hours, I recommend taking the exam at a test center—any unexpected disturbances (such as another person entering the room) could result in your exam being canceled.

1.2 Why get CCNA-certified?

Every day, thousands of people worldwide decide to begin their journey to becoming CCNA-certified. There is a good reason for that: although these days there are many competitive players in the field of networking, Cisco is still the industry leader by far. Enterprises all over the world, large and small, use Cisco devices in their networks, so it makes sense that those enterprises would want to hire people competent with Cisco devices. A job search on LinkedIn for CCNA gives many tens of thousands of results in the United States alone, and that number multiplies to hundreds of thousands worldwide.

Whether you are already in the field of IT and looking to move up the ladder to a new position or are new to the field and looking for your first job in IT, the CCNA can give you a major career advantage. A CCNA-certified person should be ready to take on job roles like network technician, network support engineer, network/systems administrator, junior network engineer, and many more. Aside from the immense value of the information you learn and the skills you acquire, simply having the CCNA on your resume is a big help in getting past the so-called HR filter and actually getting the interview. Getting a job in IT without any experience can be difficult, but being CCNA-certified will greatly improve your odds.

Although the CCNA is a networking-focused certification, it is valuable not only for those aiming for networking-specific roles. Networking is one of the foundational skills of IT, so your CCNA studies will serve you well regardless of your path. CCNA-certified professionals often move on to careers in cybersecurity, cloud, systems engineering, and other areas of IT.

Whatever your reasons are for wanting to become CCNA-certified, I promise you that you won’t regret it. IT is competitive, with many eager individuals all over the world looking to join the field. The CCNA will help you differentiate yourself and stand out from the crowd.

1.3 The structure of this book

The official CCNA exam topics list divides the topics into six logical domains. However, for a student beginning their CCNA studies, studying the topics in order from top to bottom is not ideal. Each CCNA instructor (myself included) structures their book or course differently, but no course (that I am aware of) follows the order of the exam topics list. At a very high level, the two volumes of this book cover the exam domains in the following order:

1.0 Network Fundamentals and 3.0 IP Connectivity

2.0 Network Access

3.0 IP Connectivity (again)

4.0 IP Services

5.0 Security Fundamentals

6.0 Automation and Programmability

However, you will find elements of multiple domains throughout all parts of both volumes of the book. If you are just beginning your CCNA studies, I recommend studying this book in the order I have written it; each chapter assumes you have already studied the previous chapters, so jumping around is likely to result in confusion. However, appendix A includes a chart that you can use to cross-reference the CCNA exam topics and the chapters in volumes 1 and 2 of this book. The chart should prove useful when reviewing specific exam topics before the exam.

Figure 1.1 depicts a sample network and highlights some of the various devices and protocols that make the network work. This is only a small selection of the topics we’ll delve into in this book. If you’re a newcomer to networking, you might have only heard of a few of the highlighted technologies (and probably aren’t sure how they actually work). However, at the end of both volumes of this book, you’ll be able to explain all of these technologies and more.

Figure 1.1 A local area network (LAN) connected to the internet (as represented by the cloud icon). Various devices (routers, switches, etc.) and protocols (DHCP, DNS, etc.) are highlighted. We will cover all of these technologies and more in this book’s two volumes.

1.4 How to study for the CCNA

The CCNA is a demanding exam that requires an understanding of various complex concepts, how they relate to each other, how to practically apply them in a network, and how to troubleshoot them when things go wrong. An optimal CCNA study plan should therefore take advantage of multiple resources such as a book, a video course, and practical lab exercises. Let’s examine each of these resource types and their role in effectively preparing for the CCNA exam.

1.4.1 Using a book

For many CCNA candidates, a book is where they start their CCNA studies, and for good reason. The written word is a powerful medium for conveying technical information. I want to emphasize that studying from a book differs from simply reading from a book. While you study from a book, stop occasionally to think about what you’ve just read. Take notes. Try to explain the concepts you are learning. Be an active learner, and you’ll be able to get the most out of this book and others. You don’t get more out of a book by simply reading through it multiple times. You get more out of a book by being an active learner rather than a passive learner.

1.4.2 Using a video course

A video course allows you to cover the same material studied in a book from a different angle. It’s common to hear that videos are good for developing a general understanding of a particular topic, and books are good for digging into the details. The extent to which that is true depends on which book and which video course you are using, but I would generally agree. While you don’t have to use both a book and a video course, my own experience and the experiences of many others suggest that it is beneficial. Use this book in combination with a video course of your choice, and you’ll be able to take advantage of the strengths of both mediums.

1.4.3 Lab exercises

Lab exercises (labs) are an essential part of any CCNA study plan. Labbing, a common bit of IT jargon, is a term that means getting hands-on practice with the technology you’re studying. Because this book is about the CCNA, in this context, labbing means practicing configuring Cisco routers and switches. Although there is a lot of theoretical information covered in the CCNA, it’s all for the purpose of being able to apply your skills in a real network, so labbing is an essential part of studying for the CCNA.

There are a few options available for CCNA lab practice: physical hardware, network emulators, and network simulators. Let’s take a look at each option and why I recommend using a network simulator (Cisco Packet Tracer) for the CCNA.

The first option is to use physical hardware—real Cisco routers and switches. While this may seem like the ideal approach, it is not the one I recommend for your CCNA studies. It certainly is valuable practice for an aspiring network engineer to connect and configure real physical network devices, but in terms of cost and convenience, this approach is not the best. To buy all of the necessary hardware would be cost prohibitive for most—likely many thousands of dollars. Second-hand hardware can be more affordable (you could probably assemble a viable home lab for under $1,000), but it is still too expensive for many. Second-hand devices also often run old software versions, which may not accurately represent the behavior of more recent devices.

Another option is to use a network emulation platform such as Cisco Modeling Labs (CML). CML uses virtualization technology to run virtual routers and switches, enabling you to build and run virtual networks on a personal computer or server. These virtual devices run real Cisco IOS (Internetworking Operating System, not to be confused with Apple iOS, which runs on iPhones) and allow you to configure nearly anything you would be able to on a physical Cisco router or switch. Although I would recommend this approach over physical hardware, I still do not think it is ideal. While cheaper than hardware, CML still costs around $200 per year. Additionally, running these virtual labs can require a lot of CPU and RAM resources, so unless you already have a powerful computer, you might have trouble running networks with more than a few virtual devices.

These reasons are why I think Cisco Packet Tracer is the best option for CCNA lab practice. Whereas CML is a network emulator that uses virtual machines to run real Cisco IOS, Packet Tracer is a network simulator. It is software that simulates the function of Cisco network devices but does not actually run real Cisco IOS. This makes Packet Tracer very lightweight—you do not need a powerful computer to run even very large simulated networks. Best of all, it’s free. I’m all for investing money in your studies when necessary (I’m certainly glad you invested in this book!), but when a tool like Packet Tracer is available for free, it’s hard to argue against it. Figure 1.2 shows a screenshot of a lab in Packet Tracer.

Figure 1.2 A lab in Cisco Packet Tracer. On the left is the network diagram with the lab’s instructions below it, and on the right is the CLI of one of the devices in the network.

Note Go to http://mng.bz/2Kra to download Packet Tracer for free (click Sign Up if you don’t have a Cisco account). That page also includes links to free courses from Cisco that guide you through how to download, install, and use Packet Tracer.

Although I recommend Packet Tracer, there are certainly downsides to it. Because it doesn’t run actual Cisco IOS but rather a simulated version of it, there are plenty of features and configuration commands that Packet Tracer doesn’t support. Packet Tracer only supports what its developers have programmed into it. That means that there will be some instances where a configuration command I show in this book cannot be used in Packet Tracer. However, Packet Tracer was developed as a tool for CCNA labs, so the vast majority of what we will cover in this book is supported. For studies beyond the CCNA, however, you should look into one of the other two options.

Most CCNA courses include lab exercises with them; they are essential practice. My video course includes lab exercises that will help solidify the concepts you’ve studied and build your networking skills. You can access it for free on YouTube at http://mng.bz/1G9q.

1.4.4 Using multiple resources together

So you’ve got this book, you’ve decided on a video course, and you’ve installed Cisco Packet Tracer on your computer for labs. Now what? While there is no single correct answer for how to approach your studies, the following are a couple of ideas.

One option is to focus exclusively on this book at first. Read a chapter, take notes, try to explain the concepts in your own words, and try out the configurations in Packet Tracer. Then, progress to the next chapter, and repeat the process until you have completed both volumes of this book. After that process, you may very well be ready to take on the CCNA exam, but there’s also a chance that there will be some gaps in your understanding of the concepts. To fill in those gaps, you can then follow the same process with a video course of your choice.

A second option is to use multiple resources at the same time. Study a chapter from this book, and then study the equivalent section of the video course. Do the labs provided in the course, move on to the next chapter of the book, and then repeat the process.

As I mentioned previously, there is no single correct answer. You might have to experiment to find the approach that works best for you. I will emphasize one point, though: don’t forget to do labs! Networking is a skill, and no skill can be developed only by reading a book. You have to get your hands dirty and apply what you’ve learned.

Summary

The CCNA is an exam and certification by Cisco Systems. It is the de facto industry standard entry-level networking certification.

The CCNA exam topics are divided into six domains: network fundamentals, network access, IP connectivity, IP services, security fundamentals, and automation and programmability. Each domain contains various topics and subtopics.

The CCNA exam is 120 minutes in length and consists of a variety of question types: multiple choice, single answer; multiple choice, multiple answers; drag and drop; and lab simulations.

Exam questions are randomly drawn from a large pool. Question types, order, and distribution across the exam domains are random, so each test-taker will have a different experience.

After answering or skipping a question, you can’t go back. Don’t skip a question with the intention of answering it later—this is not possible.

Don’t be afraid to guess if you don’t know the answer to a question on the exam. There is no penalty for incorrect answers.

The CCNA exam is administered by Pearson VUE and can be taken at an authorized test center or online.

Enterprises of all sizes use Cisco devices and seek CCNA-certified engineers. The knowledge and skills gained in the CCNA apply to all areas of IT—not just networking.

Study resources (including this book) do not teach the CCNA exam topics in order, from top to bottom. Rather, each instructor teaches the topics in the order they believe to be best. Use the appendix at the back of this book to cross-reference the CCNA exam topics if necessary.

Multiple study resources (book, video, labs) should be used together to solidify what you learn.

Labs can be done with physical hardware, an emulator (such as Cisco Modeling Labs), or a simulator (Cisco Packet Tracer).

Cisco Packet Tracer is the best option for CCNA labs because it is free, easy to set up, and supports most of what is needed for the CCNA.

Do your lab exercises!

Part 1. Network fundamentals

Welcome to the first leg of your journey into the intricate world of computer networking. In this first part of the book, we will set the stage for your understanding of how networks like the internet work, forming a foundation we will build upon throughout the rest of this book. When learning any new subject, the fundamentals are key, and networking is no exception. We’ll start in chapter 2 by examining the various kinds of devices that form networks: routers, switches, and firewalls—the devices that form the underlying network infrastructure—as well as the clients and servers that communicate over that infrastructure.

In chapter 3, we’ll see how we can connect those devices with copper and fiber-optic Ethernet cables. Chapter 4 takes a theoretical approach, covering the TCP/IP networking model; this is the blueprint of the internet and most modern networks, providing a theoretical framework for understanding how different network protocols function and interact. Chapter 5, on the other hand, is very hands-on; we will connect to the command-line interface (CLI) of a Cisco router and navigate through its basic command hierarchy. If you’re new to CLIs, you’ll feel like you’ve hacked into the matrix! The CLI can seem like a maze at first, but with a bit of hands-on practice, it will soon feel like a second home.

In chapter 6, we will begin delving into how networks actually enable devices to communicate with each other, focusing on how switches facilitate communication within a local area network (LAN). Then, chapter 7 addresses one of the most important topics in all of computer networking: Internet Protocol (IP) addresses. Just as a house needs an address to communicate via physical mail, a computer needs an IP address to communicate via digital messages over a network. Finally, chapter 8 focuses on Cisco router and switch interfaces, which are used to connect these network infrastructure devices.

2 Network devices

This chapter covers

The definition of a network

Types of network devices, including clients, servers, switches, routers, and firewalls

This chapter is a high-level introduction to networks and some of the different types of devices that compose them. After looking at what a network is, we will examine clients, servers, switches, routers, and firewalls. We will look at the basic roles of each of these types of devices in a network, but we won’t get into any details about how they actually perform these roles—we’ve got the rest of the book to do that! By the end of this chapter, you will be able to identify each of the network devices in figure 2.1 and briefly explain their respective roles.

Figure 2.1 An enterprise network connecting multiple offices over the internet

Each office in figure 2.1 is a local area network (LAN), a group of interconnected devices in a limited area such as an office. Within each office in the diagram, you can find the kinds of network devices we will look at in this chapter: clients, servers, switches, routers, and firewalls. The connection between offices is called a wide area network (WAN)—a network that extends over a large geographical area (such as between cities). In volume 2 of this book, we will cover several WAN connection types. The internet, as represented by the cloud icon in figure 2.1, is just one of the options for connecting remote locations.

2.1 What is a network?

What is a network? As a general term, network can refer to many different things. A system of railways connecting towns and cities is a network. The veins and arteries in our bodies can be called a network. A group of people, such as business associates, can also be called a network. What do these all have in common? They are all about connecting people or things. In this book’s two volumes, we are looking at a specific kind of network: a computer network—a network that connects computers. A computer connected to a network can be many different things, including

A personal computer connected to the internet via a home network

A television that connects to the internet to stream Netflix

An iPhone connected to the internet via wireless 5G

A YouTube server that streams videos to devices all over the world

An enterprise’s servers that store private files and data

A security camera that saves footage to a server

We can define a computer network as a telecommunications network that allows nodes to share resources. That definition is certainly short and sweet, but you might be left with a couple of questions, like What is a node? and What is a resource?

A node is any device that connects to a network. It includes the previously listed examples, like a personal computer or an iPhone, as well as the network infrastructure that connects the devices—the routers, switches, firewalls, and various other types of devices that make up the network.

A resource is anything that can be accessed or used over the network. For example, if you use a web browser such as Google Chrome to access manning.com, the webpage that appears on your screen is a resource shared over the network. It is a file located on a server somewhere on the internet, and that server shares the webpage with the device you use to access the website. However, resources aren’t just files. There are countless examples, but here are a few:

A printer that is connected to the network and shared by users in an office

An online game server that supports multiplayer gaming

Cloud-based software like Gmail and Microsoft 365

2.2 Types of network devices

The previous discussion of nodes and resources leads us to this section. Let’s look at the types of nodes that share resources over a network, as well as the types of nodes that comprise the network infrastructure that facilitates the sharing of resources.

2.2.1 Clients and servers

First, we will look at the nodes that share resources over a network: clients and servers. We cannot understand one without understanding the other because they are defined by their relationship with each other: a client is a device that accesses a service provided by a server, and a server is a device that provides services for clients. Figure 2.2 shows the icons for clients and servers that we will be using throughout this book.

Figure 2.2 Icons representing a desktop computer and a file server. Icons like these are commonly used in network diagrams to represent clients and servers.

It’s important to note that clients and servers aren’t specific types of physical devices. Rather, they are roles that can be assumed by a variety of devices. If a device provides a service, such as hosting a webpage, that device is functioning as a server. If a device accesses a service, such as retrieving a webpage from a server, that device is functioning as a client.

Note The term server is also used to refer to a kind of device—a very powerful computer designed to be able to provide services to many clients, such as a YouTube server streaming video to thousands of clients over the internet. However, almost any kind of device can function as a server, so it’s better to think of a server as a role, not a specific kind of device.

Let’s list a few examples of client–server pairs:

Client—A network-enabled TV that streams a movie on Netflix

Server—A Netflix server that hosts the movie and sends it over the network

Client—An iPhone scrolling through X (formerly Twitter)

Server—X servers that host the tweets and send them to the iPhone

Client—A PC accessing an Excel spreadsheet located on an enterprise’s server

Server—An enterprise’s server containing spreadsheets and other internal files

Almost any node can be both a server and a client, depending on the context. For example, in a home network, it’s possible to share files among devices. You can transfer a movie file from one PC to another PC in the network. In that case, the PC where the movie file is located is a server, and the PC accessing the file is a client. If the file was shared in the opposite direction, the server and client roles would be reversed. And both PCs would be clients when they are accessing websites over the internet. Figure 2.3 shows a client–server relationship between two PCs.

Figure 2.3 Two desktop PCs sharing a file. The PC on the left is functioning as a client, and the PC on the right is functioning as a server.

Note Both devices in figure 2.3 use the client icon to emphasize that they are both PCs—the same kind of device—but their roles are different in this exchange.

Sometimes a network is as simple as two devices directly connected to each other. However, this type of connection is rare. To expand the network and allow more devices to communicate with each other, we need some specific types of devices to act as the network infrastructure and facilitate that communication.

Client and server nodes are often called endpoints or end hosts. These are general terms for devices that communicate over a network, as opposed to the network infrastructure devices that connect the end hosts.

2.2.2 Switches

Let’s build out the network further by connecting our end hosts to a switch, as in figure 2.4.

Figure 2.4 Three end hosts connected to a switch

Devices connected to a switch are able to communicate with each other via the switch. Note that they do not typically communicate with the switch itself—the switch only serves as infrastructure over which communication can occur.

The role of a switch is to connect devices within a LAN. For example, all of the PCs, security cameras, printers, servers, and other devices in an office are probably connected to one or more switches. For this reason, it’s common for switches to have many ports for end hosts to connect to—usually from 24 to 48 per switch.

Note A port is a physical connector on a device. Devices are physically connected by connecting one end of a cable to each of two devices. A port serves as the interface between one device and the other devices in the network. For that reason, the terms port and interface are often used interchangeably.

Switches use a variety of technologies to facilitate communications between the devices connected to them. In chapter 6, we will begin to learn exactly how switches do this. For now, it’s sufficient to know their basic purpose. Note that the role of a switch is not to provide connectivity between LANs or to external networks. For example, you would not connect a switch directly to the internet. For that, we need another type of device.

2.2.3 Routers

So far, we’ve connected end hosts to a switch to allow them to communicate with each other. Switches provide connectivity among devices within a LAN, but chances are we want our end hosts to be able to communicate with external networks, too. For example, for end hosts to communicate over the internet, we need a device that provides connectivity between LANs and the internet. That type of device is called a router. Figure 2.5 shows how routers are used to connect LANs to external networks, such as the internet.