• Course Introduction

        • Time: 38 hours
        • Free Certificate
        The Internet has become one of the most important components of our life. We browse the Web, check e-mails, make VoIP phone calls, and have video conferences via computers. These applications are made possible by networking computers together, and this complex network of computers is usually referred to as the Internet. This course is designed to give you a clear understanding of how networks, from in-home local area networks, or LANS, to the massive and global Internet, are built and how they allow us to use computers to share information and communicate.

        Unit 1 introduces you to an explanation of computer networks and some basic terminology fundamental to understanding computer networks. You will also familiarize yourself with the concept of layers, which compose the framework around which networks are built. Next, Unit 2 explains the concept of protocols. A computer communication (or network) protocol defines rules and conventions for communication between network devices.

        The rest of the course implements a top-down approach to teach you the details about each layer and the relevant protocols used in computer networks. Beginning in Unit 3, you will explore the concept of application layer protocols, which include the Domain Name System, e-mail protocols, and the Hypertext Transfer Protocol. Unit 3 ends with an overview of how to use socket programming to develop network applications. In Unit 4, you will learn transport layer protocols, including the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP). You will go on to study the network layer Internet Protocol (IP) and packet routing protocols in Unit 5. Next is Unit 6, devoted to a discussion on link layer protocols, and the course concludes with an overview of voice and video protocols, network security, and cloud computing in Unit 7. As you move through the course, notice how the layers build on top of one another and work together to create the amazing tool of computer networks, which many of us depend upon daily.

        • Course Syllabus

          First, read the course syllabus. Then, enroll in the course by clicking "Enroll me". Click Unit 1 to read its introduction and learning outcomes. You will then see the learning materials and instructions on how to use them.

        • Unit 1: Networking Fundamentals

          When you think of networking, what is the first word that comes to mind? If you answered "internet", you are correct. The Internet is an example of a massive computer network. Computer networks make it possible for one device to communicate with another device. Another example of a computer network is the local area network or LAN. If you can access all of the desktops, laptops, wireless devices, and printers in your workplace, college, or home, you have a LAN.

          This unit will introduce the basic concept of a computer network and arm you with the tools you will need to work through the more technical aspects of this course. You will look at the different types of networks, with the primary focus on the LAN. The unit continues with an introduction to layers, which are central to understanding how computer networks operate. You will also become familiar with Request for Comments (RFC) documents, which are standards that define all of the Internet protocols. RFCs are created by The Internet Engineering Task Force (IETF).

          The concepts presented in this course will provide the background information needed to develop network applications, take a network certification course, or communicate with networks neighboring your LAN.

          Completing this unit should take you approximately 3 hours.

        • Unit 2: The Basics of Protocols

          In life, protocols define how we interact with others – for example, how we behave in a public place. In computer science, protocols are formal sets of rules that dictate how computers communicate with one another over a network medium. Protocols constitute the backbone of networking. The standard networking protocol and distributed application model is the International Standard Organization's Open System Interconnect (ISO/OSI) model. The Internet protocol stack TCP/IP (Transmission Control Protocol/Internet Protocol) model presents a group of protocols optimized for inter-computer communications, particularly communications between multiple applications that may run on one computer. This unit provides an overview of the TCP/IP stack and its different layers, identifies the function of each layer, introduces the basics of how computers talk to one another in cyberspace using TCP/IP protocols, describes the techniques for wide area networks, and discusses standard transmission media for the Internet.

          Completing this unit should take you approximately 2 hours.

        • Unit 3: The Application Layer

          In this unit, we will examine the application layer of the TCP/IP stack. The application layer is where all network processes and applications run. We will explore five of this layer's prominent applications: the Domain Name System (DNS), e-mail protocols, the World Wide Web's Hypertext Transfer Protocol (HTTP), Simple Network Management Protocol (SNMP), and Secure Shell (SSH). Finally, we will discuss socket programming and how it can be used to develop network applications.

          Completing this unit should take you approximately 5 hours.

        • Unit 4: The Transport Layer (TCP/UDP)

          When we talk about networks, we are talking about data transport. The TCP/IP stack provides a TCP/UDP layer that handles the data transport between machines across networks. In this unit, you will learn the TCP and UDP protocols by examining the structure of TCP and UDP segments and identifying how this layer serves as the application layer in the TCP/IP stack.

          Each application relies on the transport layer that is described in this unit. It is a key layer in today's networks, containing all the mechanisms necessary to deliver reliable data over an unreliable network. First, we will develop a simple, reliable transport layer protocol. Then, we will link the details of the TCP and UDP protocols used in TCP/IP networks. We will also study Stream Control Transmission Protocol (SCTP) and Real-Time Transport Protocol (RTP). These protocols are the fundamental protocols for modern multimedia applications over the Internet.

          Completing this unit should take you approximately 5 hours.

        • Unit 5: The Network Layer

          In this unit, we will learn how packets (groupings of data) travel on a network and how each machine can be addressed uniquely so that data transport between two nodes is reliable. We will learn that networks can run out of space, meaning that unique addresses for different machines are no longer available. In these situations, computer scientists must manage IP addressing using CIDR and subnetting – techniques we will learn about in this unit.

          The network layer is responsible for the delivery of packets from any source to any destination through intermediate routers. Follow the links to explore in detail the IPv4, IPv6, RIP, OSPF, and BGP protocols used in today's Internet.

          Completing this unit should take you approximately 10 hours.

        • Unit 6: The Link Layer

          The final layer of the TCP/IP protocol stack that we discuss is the link layer. This unit will explain how you can address machines on a network from that layer, use IP addresses to determine physical addresses, and identify the mechanisms in the link layer that can correct packet collisions when data is transferred over the wire. This unit discusses the link layer by focusing on how multiple hosts share one transmission medium. The unit ends with a detailed discussion of the two types of computer networks that are important today from a deployment perspective: Ethernet and Wi-Fi.

          Completing this unit should take you approximately 7 hours.

        • Unit 7: Multimedia, Security, and Cloud Computation over the Internet

          Multimedia over the Internet is incredibly popular. This unit discusses the protocols for transmitting multimedia content like voice and video over the Internet. It discusses security, reliability, and fault tolerance issues related to Internet applications. We also introduce cloud computing and briefly discuss network remote access and directory services.

          Completing this unit should take you approximately 6 hours.

        • Study Guide

          This study guide will help you get ready for the final exam. It discusses the key topics in each unit, walks through the learning outcomes, and lists important vocabulary. It is not meant to replace the course materials!

        • Course Feedback Survey

          Please take a few minutes to give us feedback about this course. We appreciate your feedback, whether you completed the whole course or even just a few resources. Your feedback will help us make our courses better, and we use your feedback each time we make updates to our courses.

          If you come across any urgent problems, email contact@saylor.org.

        • Certificate Final Exam

          Take this exam if you want to earn a free Course Completion Certificate.

          To receive a free Course Completion Certificate, you will need to earn a grade of 70% or higher on this final exam. Your grade for the exam will be calculated as soon as you complete it. If you do not pass the exam on your first try, you can take it again as many times as you want, with a 7-day waiting period between each attempt.

          Once you pass this final exam, you will be awarded a free Course Completion Certificate.

        • Saylor Direct Credit

          Take this exam if you want to earn college credit for this course. This course is eligible for college credit through Saylor Academy's Saylor Direct Credit Program.

          The Saylor Direct Credit Final Exam requires a proctoring fee of $5. To pass this course and earn a Proctor-Verified Course Certificate and official transcript, you will need to earn a grade of 70% or higher on the Saylor Direct Credit Final Exam. Your grade for this exam will be calculated as soon as you complete it. If you do not pass the exam on your first try, you can take it again a maximum of 3 times, with a 14-day waiting period between each attempt.

          We are partnering with SmarterProctoring to help make the proctoring fee more affordable. We will be recording you, your screen, and the audio in your room during the exam. This is an automated proctoring service, but no decisions are automated; recordings are only viewed by our staff with the purpose of making sure it is you taking the exam and verifying any questions about exam integrity. We understand that there are challenges with learning at home - we won't invalidate your exam just because your child ran into the room!


          1. Desktop Computer
          2. Chrome (v74+)
          3. Webcam + Microphone
          4. 1mbps+ Internet Connection

          Once you pass this final exam, you will be awarded a Credit-Recommended Course Completion Certificate and can request an official transcript.