Introduction to Computer Networking - Beginner Crash Course

This lesson describes the differences between hubs, switches, and bridges in a Layer 2 Ethernet network. It explains the concepts of MAC tables, broadcast traffic, and Broadcast and Collision domains.

In this video, we explore the OSI model, a framework used to understand networking through its seven layers, focusing on how it simplifies the complexities of network communications. While we briefly touch on the higher layers (application, presentation, and session), the emphasis is on the more relevant lower layers (transport, network, data link, and physical) for networking professionals, using an example of uploading a video to YouTube to demonstrate the OSI model in action.

This video explains how Ethernet switches learn MAC addresses and populate their MAC address tables. When a device sends traffic, the switch records the source MAC address and associates it with the port where the frame was received. The video covers MAC learning, port mappings, how aging timers remove inactive entries, and how multiple MAC addresses can appear on a single port when additional network devices are connected. Key terms include MAC address, switch port, MAC table, Ethernet frame, learning process, aging, forwarding, and Layer 2 switching.

This video explains how BUM traffic—broadcast, unknown unicast, and multicast—operates on an Ethernet network. It covers how ARP requests generate Layer 2 broadcasts, how switches flood unknown unicast frames when the destination MAC address is not in the MAC table, and how multicast traffic is forwarded only to ports that belong to a multicast group. Key concepts include MAC addresses, IP addressing, ARP tables, MAC learning, Layer 2 flooding, inter-switch links, multicast groups, Ethernet frames, and multi-destination traffic behavior.

Learn how Layer 3 routers connect Layer 2 switches and Ethernet segments (VLANs). Understand the impact of routers on MAC tables, ARP requests, and L2 broadcasts. Learn about route tables and default gateways.

This video explains the key differences between TCP and UDP at Layer 4. Topics include connectionless delivery, datagrams, TCP’s connection-oriented behavior, acknowledgements, retransmissions, sequence numbers, checksums, error detection, reliable transport, packet loss handling, and payload integrity. The lesson covers how UDP provides best-effort delivery for applications like VoIP, while TCP ensures accuracy for web browsing, downloads, and email. Key terms: TCP segments, UDP datagrams, OSI Layer 4, reliability, checksum calculation, sequence numbers, acknowledgement packets, corrupted data detection, retransmission process, and Layer 4 transport protocols.

This video explains Power over Ethernet (PoE) and how Ethernet cables can deliver electrical power to devices. It covers the differences between PoE (15.4W), PoE+ (30W), and PoE++/Type 4 (up to 100W), as well as device compatibility requirements. Key concepts include PoE switch capability, power budgets, wireless access points, IP phones, Ethernet cabling, power delivery standards, and network hardware support. The lesson provides a clear overview of how PoE simplifies device deployment and eliminates the need for separate electrical outlets.

This video explains the structure of IP addresses and how subnets define network and host portions. It covers octets, private IP ranges, slash notation, subnet masks, /24 and /16 subnet examples, address ranges, and reserved subnet addresses including the network address, first usable host, default gateway, and broadcast address. Additional topics include breaking a large /16 network into smaller /24 subnets, using a subnet calculator, host capacity, and understanding how subnet boundaries affect routing and segmentation.

Follow an IP packet as it flows from a computer, through a switch, and through a router. Understand source and destination IPs, and how they are processed by the route table. Learn about Layer 2 and Layer 3 of the OSI model. Understand how the ARP table is used to associate MAC addresses with IP addresses.

This lesson explains the Internet Control Message Protocol (ICMP) and how tools like Ping and Traceroute use it to test connectivity and diagnose network issues. You’ll learn how ICMP fits into the OSI model, why TTL (Time to Live) values matter, and how latency results help identify network performance problems.

Understand how VLANs (Virtual LANs) are used to created multiple Layer 2 logical segments in an Ethernet switch. Learn how VLANs can be used to enhance network security. Understand the difference between trunk and access ports on a switch.

Understand Wide Area Connections (WAN) and how they are used to connect networks over long distances. Work with a newtowk diagram to understand how traffic is routed over a WAN. Understand the basic concepts of static routes vs. Dynamic routing protocols like OSPF and BGP.

In this lesson, you’ll see how local area networks connect to the wider internet using a border router. We’ll discuss internet service providers, bandwidth vs. speed, and why the border router is the first line of defense for your network.

Understand how IPSEC VPNs (Virtual Private Networks) are used to securely connect networks using encryption over an untrusted network like the Internet. Learn how public IP addresses are used to enable an IPSEC VPN.

Learn how L2 (Layer 2) VPNs (Virtual Private Networks) are used to extend a network segment over long distances, and how they use encryption to secure traffic. Understand the impact of a L2 VPN on the IP addressing scheme. Understand how Layer 2 VPNs can be used to help with DR (Disaster Recovery) and also achieve VM (Virtual Machine) mobility.

In this lesson, we explore how mobile internet technologies like 5G and LTE provide connectivity for both personal devices and corporate networks. You’ll learn how these networks differ in speed and latency, how devices switch between them, and how businesses can use 5G/LTE as backup or even primary connections in certain scenarios.

This lesson introduces Software-Defined Wide Area Networking (SD-WAN) and explains how it uses multiple internet connections to intelligently route traffic. You’ll see how SD-WAN prioritizes critical applications, enables secure VPN connections to headquarters and cloud services, and improves reliability through automatic failover and flexible routing.

This lesson explains the key networking concepts of latency and jitter. Latency is the time it takes for data to travel across a network, while jitter is the variation in that travel time. Using real-world analogies like mailing a letter (latency) and buses arriving at different times (jitter), you’ll learn how these factors impact performance in applications like video calls, gaming, and streaming.

This lesson introduces fiber optic technology, which uses light instead of electricity to transmit data. You’ll learn how fiber cables work through total internal reflection, why they are faster and more reliable than copper, and the differences between single-mode and multi-mode fibers. We’ll also cover common uses, such as internet backbones, data centers, and even medical devices.

The lesson covers the importance of network redundancy in maintaining continuous network operations despite component failures. It explains how to identify single points of failure, implement redundancy strategies such as installing redundant components and using protocols like HSRP or VRRP, and ensure automated failover through dynamic routing protocols.

This lesson on DNS basics provides an essential understanding of the Domain Name System. Students will learn how DNS translates user-friendly domain names into IP addresses, enabling seamless internet navigation. They will also delve into the hierarchical structure of DNS and the role of authoritative name servers. We will also learn about handy DNS commands including nslookup.

In this lesson, we introduce the core concepts of load balancing and why it is essential for modern applications. You’ll learn how load balancers distribute incoming traffic across multiple servers to improve performance, ensure high availability, and support scalability. We’ll also explore how listeners and health checks work, and see how load balancing applies both in traditional data centers and cloud environments.

This video introduces foundational concepts of network troubleshooting, emphasizing a methodical approach to isolate and identify issues within various network setups. The instructor uses a hypothetical scenario involving server communication problems to demonstrate how using a network diagram and systematically eliminating potential causes can streamline the troubleshooting process, urging a slow yet deliberate strategy to quickly resolve network issues.

This DHCP lesson introduces students to the fundamental concepts of Dynamic Host Configuration Protocol. In this lesson, learners will discover how DHCP simplifies network management by automatically assigning IP addresses and network configurations (Including DNS servers) to devices. Differentiate between static and dynamic IP addresses.

This lesson introduces NetFlow and IPFIX, protocols essential for analyzing and monitoring network traffic to troubleshoot problems and identify intermittent network issues. It highlights the differences between NetFlow, a Cisco-specific protocol, and IPFIX, an industry standard, and their roles in capturing traffic data for comprehensive network visibility and security.

This lesson covers the fundamentals of the Network Time Protocol (NTP), highlighting its critical role in synchronizing time across all network devices to ensure accurate log interpretation, event management, and the validity of digital certificates. It explains the process of selecting an authoritative NTP source and configuring network devices to maintain consistent timing, emphasizing the importance of using reliable time sources like the Naval Observatory or NIST.

This lesson introduces AI-assisted networking and shows how AI can automate repetitive tasks, detect anomalies, and optimize network performance. You’ll also learn about current vendor solutions from Cisco, VMware, and Juniper.

In a foundational lesson on Public IP addresses, private IP addresses, and Network Address Translation (NAT), students will grasp the core principles of IP addressing. They'll learn that public IP addresses are unique identifiers assigned to devices on the open internet, while private IP addresses are used within local networks to conserve public addresses and enhance security. The lesson will also explain how NAT serves as a bridge between private and public addresses, enabling multiple devices in a local network to share a single public IP for internet access, making it an integral component of modern network setups.

This lesson introduces the concept of firewall zones, with a focus on the Demilitarized Zone (DMZ) and its real-life analogy in the context of network security. The DMZ is explained as an intermediate area between trusted internal networks and untrusted external networks, emphasizing the need for strict control of traffic to and from the DMZ. The lesson highlights the importance of firewalls in controlling and securing the flow of traffic between these different zones to protect sensitive data and systems while allowing controlled accessibility from external sources.

This lesson introduces classic network firewalls that filter traffic by IPs (Layer 3) and ports/protocols (Layer 4). You’ll see how ACL rules are evaluated top-down, how to “allow only what you need” and end with an implicit deny-all, and how to differentiate egress (outbound) vs ingress (inbound) controls. We walk through practical examples (HTTP/HTTPS/DNS permits, SMTP blocks), show why rule order matters, and place these controls at network boundaries—Internet edge and DMZ—to tightly restrict exposed services.

This lesson explains how Layer 7 firewalls, also called next-generation firewalls, go beyond basic port and IP filtering to perform deep packet inspection. Instead of only looking at the “envelope” (address and port), they open the “letter” to analyze application-level traffic. By using signature databases and behavioral analysis, Layer 7 firewalls can detect and block attacks that masquerade as normal traffic, providing stronger protection against modern threats.

In this lesson, we explore the fundamentals of intrusion detection and prevention. You’ll learn how IDS passively monitors and alerts on suspicious activity, while IPS actively blocks malicious traffic in real time. We also compare signature-based and behavior-based detection methods, and discuss how these systems help protect against both known and zero-day threats.

This lesson explains how VPN services like NordVPN and Surfshark work, detailing their use of encryption and secure servers to protect user privacy, mask IP addresses, and bypass geographic restrictions. It also explores the benefits, drawbacks, typical costs, and the risks VPNs help eliminate.

This lesson on the basic concepts of Wi-Fi introduces students to wireless networking technology. Learners will discover how Wi-Fi enables devices to connect to the internet or local networks without physical cables. They will explore key elements such as Wi-Fi routers, access points, and SSIDs.

In this IP addressing Crash Course, we'll cover fundamental networking concepts, ensuring clarity even for those with limited networking knowledge. The course focuses on essential IP addressing elements with hands-on exercises, providing a concise and practical foundation without unnecessary details, and by the end of the two-hour journey, you'll have a robust understanding of IP addressing.

In this video, we delve into the significance of IP addresses in the context of the vast network of interconnected devices on the Internet. Drawing an analogy to physical addresses, IP addresses serve as unique identifiers, allowing efficient routing and delivery of data, contrasting them with local MAC addresses. The video also introduces the concept of DNS queries, illustrating how computers translate user-friendly domain names like Google.com into the numerical IP addresses essential for global communication on the Internet.

This lesson explores the distinctions between public and private IP addresses, drawing parallels to phone extensions within an organization. Public IP addresses are globally routable and used on the internet, similar to unique phone numbers. They must be assigned by internet service providers or cloud service providers and are often employed for routers and firewalls facing the internet. Private IP addresses, on the other hand, are used within local networks and can have the same addresses as other private IPs in different networks because they are not globally routable, akin to local phone extensions that work only within their respective office buildings. The lesson also introduces the concept of Network Address Translation (NAT), which allows devices with private IP addresses to access the internet by translating their private IPs to a single public IP.

In this lesson, the instructor uses an example IP address from their computer's configuration to break down the structure of an IP address. They discuss the format of IP addresses with four octets separated by periods (dotted decimal format) and explain the distinction between network and host addresses, with a brief mention of the default gateway as the route for traffic leaving the local network. The lesson serves as an introductory exploration of IP address components and sets the stage for more in-depth coverage of related concepts in subsequent lessons.

In this lesson, the instructor explains the difference between classful and classless addressing in the context of IP addresses. They discuss the historical development of class A, class B, and class C address ranges and how these classes had limitations in terms of address allocation. The lesson introduces the concept of variable length subnet masking (VLSM) as a more flexible approach to address allocation, enabling organizations to receive IP address ranges that better match their actual needs and avoiding the waste of address space.

In this lesson, the instructor demonstrates how to convert between binary and decimal numbers, a fundamental skill in understanding IP addresses and subnet masks. The lesson provides a step-by-step guide to converting a decimal number to binary, starting with the largest binary value and progressively subtracting to find the binary digits. It also shows how to convert an entire IP address from decimal to binary format. The process is illustrated with examples for better comprehension, emphasizing the importance of these skills when working with IP addresses and subnet masks in networking.

This lesson explains why the maximum value for an octet in an IP address is 255. It demonstrates how to calculate the maximum value by setting all binary digits to 1, resulting in 255 when summed. Understanding this concept is crucial for comprehending IP addresses and subnet masks, as it highlights the fundamental binary structure that underlies IP addressing.

In this lesson, learners are guided through the process of converting IP addresses to binary format. The instructor presents a practice exercise where students are asked to convert the IP address "192.168.1.10" to binary. A downloadable PDF file with exercises is also available for further practice.

This video simplifies the concept of subnetting, illustrating how dividing a larger network into smaller segments improves efficiency, security, and IP address management. Using a class B network example, the instructor explains how subnetting allows for departmental traffic segregation within an organization, enhancing security and reducing IP address wastage by allocating just the necessary amount of address space to each subnet.

In this lesson, learners are introduced to the concepts of subnetting with a focus on understanding subnet masks, CIDR notation, and identifying network and host portions of IP addresses. The instructor explains the principles of subnetting by providing examples, demonstrating how to determine network and broadcast addresses, and using CIDR notation to represent subnets of different sizes. The lesson also emphasizes the importance of understanding subnetting for customizing network sizes and optimizing address allocation.

In this video, the instructor explains how to calculate the number of hosts in a subnet using subnet masks. The lesson starts with a simple subnet mask (255.255.255.0) and then progresses to more complex subnet masks (e.g., 255.255.252.0, 255.255.248.0) to illustrate the concept of host bits. Learners are guided through the process of identifying host bits in binary representations and determining the number of usable host IP addresses. The lesson emphasizes the importance of understanding these calculations to master subnetting effectively.

In this video, the instructor presents additional exercises related to CIDR notation and understanding subnet masks. Learners are tasked with converting subnet masks to CIDR notation and determining the range of IP addresses in a given subnet. The video covers how to calculate network addresses, broadcast addresses, and the number of usable addresses in a subnet, emphasizing the importance of understanding these concepts and using a subnet calculator to validate the answers. The exercises provide practical examples for learners to practice and reinforce their subnetting skills.

In this video, the instructor demonstrates how to take a large network and divide it into multiple smaller subnets. The example starts with a /16 network and the goal is to create four subnets, two supporting 1000 devices each and two supporting 400 devices each while keeping the subnets as small as possible. The instructor explains how to calculate the required CIDR notation for each subnet and provides a step-by-step breakdown of the process, highlighting the importance of designing efficient subnets. The video also emphasizes the value of practice to gain proficiency in subnetting.

In this video, the focus is on understanding the special addresses within an IP network, particularly in the context of a subnet with the example of 10.1.1.0/24. The instructor explains the roles of the network address (10.1.1.0), the first usable address (10.1.1.1), and the broadcast address (10.1.1.255) within the subnet. These addresses have specific purposes and are reserved, while the range from 10.1.1.2 to 10.1.1.254 is available for assigning to devices in the network.