Computer Networks

Computer Networking

Networking from the wire to the browser - packets, IP and subnetting, routing, TCP/UDP, DNS, HTTP, TLS, load balancing, CDNs and sockets. 18 modules built for real debugging and system-design interviews.

Beginner1270123 lessons48 free lessonsnetworkingcomputer-networkstcp-ipdnshttp

Computer Networking

Everything an engineer needs to reason about the network - not as trivia, but as the thing that actually breaks in production and gets probed in interviews.

The course walks the stack end to end: what a packet is and how it travels, the layered models and how to see them in Wireshark, physical and link-layer realities including WiFi, IP addressing and subnetting (with practice), routing and NAT, the transport layer with TCP's mechanics and UDP's trade-offs, DNS, HTTP and the modern web protocols, network security and TLS, application protocols, load balancing, CDNs, sockets and connection pooling, cloud and multi-region networking, and a full debugging and performance toolkit.

It closes with a networking checklist for system-design interviews and a vocabulary reference you can revise from.

Early modules are free to preview. The full course is a one-time purchase with lifetime access.

What you will learn

• Trace exactly what happens when a URL is typed - DNS, TCP, TLS, HTTP, render
• Subnet confidently: CIDR, address classes, IPv6, and NAT in practice
• Explain TCP properly - handshake, flow control, congestion, and when UDP wins
• Debug real network problems with ping, traceroute, dig, netstat and Wireshark
• Design with load balancers, CDNs, and connection pooling - and justify the choice
• Reason about TLS, OAuth, JWT and the common application-security failures
• Handle cloud networking: VPCs, virtual networks, and multi-region traffic
• Answer networking questions in system-design interviews with real depth

Prerequisites

• Basic command-line comfort
• No prior networking knowledge required - module 0 starts from first principles

Course outline

Module 1: Networking Foundations

Networking Foundations - 5 topics.

• What Is Computer Networking And Why Should You Care 10 min read
• The Internet A 10000 Foot View 10 min read
• What Happens When You Type A Url And Press Enter 10 min read
• Clients Servers And The Request Response Model 10 min read
• Packets How Data Actually Travels 11 min read

Module 2: Network Models: OSI and TCP/IP

Network Models: OSI and TCP/IP - 7 topics.

• Why Do We Need Network Models 10 min read
• The Osi Model All Seven Layers Explained 12 min read
• The Tcpip Model What The Internet Actually Uses 11 min read
• Osi Vs Tcpip Which One Matters 11 min read
• Encapsulation And Decapsulation 10 min read
• Protocols The Rules Of Communication 10 min read
• Hands On Seeing Layers In Action With Wireshark 11 min read

Module 3: Physical and Data Link Layers

Physical and Data Link Layers - 7 topics.

• The Physical Layer Signals Media And Hardware 10 min read
• Ethernet The Foundation Of Local Networks 10 min read
• macOS / Linux 10 min read
• Switches And Hubs Moving Data On A Local Network 10 min read
• Vlans Virtual Local Area Networks 10 min read
• Linux / macOS 10 min read
• Wifi And Wireless Networking 10 min read

Module 4: IP Addressing and Subnetting

IP Addressing and Subnetting - 8 topics.

• What Is An Ip Address 10 min read
• Ipv4 Address Classes And Ranges 10 min read
• Subnetting Dividing Networks 11 min read
• Linux/macOS - using ipcalc 11 min read
• Ipv6 The Next Generation 11 min read
• Nat Network Address Translation 10 min read
• Dhcp Automatic Ip Assignment 10 min read
• Basic ping 11 min read

Module 5: Routing and Forwarding

Routing and Forwarding - 7 topics.

• View the routing table 10 min read
• Add a static route: traffic for 10.0.2.0/24 goes via 10.0.1.1 10 min read
• Distance Vector Routing Rip 10 min read
• Link State Routing Ospf 10 min read
• Bgp How The Internet Routes Between Organizations 10 min read
• Ip Fragmentation And Mtu 10 min read
• Nat In Routing Context 10 min read

Module 6: The Transport Layer and TCP

The Transport Layer and TCP - 8 topics.

• Server socket creation (simplified) 10 min read
• Tcp Three Way Handshake 10 min read
• Tcp Reliable Data Transfer 10 min read
• Tcp Flow Control Sliding Window 10 min read
• Tcp Congestion Control 10 min read
• Tcp Connection Termination 10 min read
• Tcp Hol Blocking And Limitations 10 min read
• Summary statistics (total connections by state) 11 min read

Module 7: UDP and Choosing a Transport

UDP and Choosing a Transport - 6 topics.

• UDP Server 10 min read
• Tcp Vs Udp When To Choose Which 10 min read
• Quic Protocol For Http3 11 min read
• Rtp And Real Time Streaming 10 min read
• Multicast And Broadcast 10 min read
• Comparing Transport Protocols 11 min read

Module 8: DNS

DNS - 7 topics.

• What Is Dns 10 min read Pro lesson
• Dns Resolution Step By Step 10 min read Pro lesson
• Dns Record Types 11 min read Pro lesson
• Dns Caching And Ttl 10 min read Pro lesson
• Dns Load Balancing 11 min read Pro lesson
• Dns Security 10 min read Pro lesson
• Query multiple domains 11 min read Pro lesson

Module 9: HTTP and Web Protocols

HTTP and Web Protocols - 8 topics.

• Http Fundamentals 10 min read Pro lesson
• Http Methods 11 min read Pro lesson
• Http Status Codes 10 min read Pro lesson
• Http Headers 10 min read Pro lesson
• Cookies Sessions State 10 min read Pro lesson
• Http2 10 min read Pro lesson
• Http3 Quic 10 min read Pro lesson
• Rest Graphql Grpc 11 min read Pro lesson

Module 10: Network Security and TLS

Network Security and TLS - 8 topics.

• Why Network Security Matters 10 min read Pro lesson
• Symmetric Vs Asymmetric Encryption 10 min read Pro lesson
• Tls Handshake 10 min read Pro lesson
• Digital Certificates And Cas 11 min read Pro lesson
• Https Http Over Tls 11 min read Pro lesson
• Common Network Attacks 10 min read Pro lesson
• Allow established and related connections 10 min read Pro lesson
• Oauth Jwt App Security 11 min read Pro lesson

Module 11: Application Protocols

Application Protocols - 7 topics.

• Smtp Imap Pop3 10 min read Pro lesson
• Ftp Sftp 10 min read Pro lesson
• Ssh 10 min read Pro lesson
• Mqtt Iot 10 min read Pro lesson
• Amqp Kafka 10 min read Pro lesson
• Dhcp Ntp Infrastructure 11 min read Pro lesson
• Protocol Design Principles 10 min read Pro lesson

Module 12: Beyond HTTP: Realtime and Streaming

Beyond HTTP: Realtime and Streaming - 6 topics.

• Why Http Not Enough 10 min read Pro lesson
• Short Long Polling 10 min read Pro lesson
• Sse 10 min read Pro lesson
• Websockets 10 min read Pro lesson
• Webrtc 10 min read Pro lesson
• Decision Framework 11 min read Pro lesson

Module 13: Load Balancing

Load Balancing - 7 topics.

• What Is Load Balancing 10 min read Pro lesson
• Load Balancing Algorithms 10 min read Pro lesson
• L4 Vs L7 10 min read Pro lesson
• Reverse Proxy 11 min read Pro lesson
• Health Checks Failover 11 min read Pro lesson
• Gslb 10 min read Pro lesson
• /etc/nginx/nginx.conf 11 min read Pro lesson

Module 14: Content Delivery Networks

Content Delivery Networks - 6 topics.

• What Is A Cdn 10 min read Pro lesson
• Cdn Architecture 10 min read Pro lesson
• Cdn Caching Strategies 11 min read Pro lesson
• Cdn Dynamic Content 10 min read Pro lesson
• Cdn Providers 10 min read Pro lesson
• Cdn System Design 11 min read Pro lesson

Module 15: Sockets and Connection Management

Sockets and Connection Management - 7 topics.

• Create a socket - the OS allocates a kernel data structure 10 min read Pro lesson
• Demonstration (would normally run as separate process) 10 min read Pro lesson
• Demonstration 11 min read Pro lesson
• poll() uses a polling object 10 min read Pro lesson
• Non-blocking connect - returns immediately 10 min read Pro lesson
• Http Server From Scratch 10 min read Pro lesson
• Without connection pooling (BAD) 11 min read Pro lesson

Module 16: Cloud and Virtual Networking

Cloud and Virtual Networking - 7 topics.

• Physical To Virtual Networks 10 min read Pro lesson
• Vpc 11 min read Pro lesson
• Security Groups Nacls 10 min read Pro lesson
• Service Discovery Mesh 10 min read Pro lesson
• Example: Allow ingress to api pods only from web pods on port 8080 11 min read Pro lesson
• Api Gateways Ingress 10 min read Pro lesson
• Multi Region Networking 11 min read Pro lesson

Module 17: Network Debugging and Performance

Network Debugging and Performance - 7 topics.

• Network Debugging Mindset 11 min read Pro lesson
• Capture all traffic on port 8080 11 min read Pro lesson
• Capture all traffic on port 443, save to file 10 min read Pro lesson
• Latency 10 min read Pro lesson
• Server side (receiver) 11 min read Pro lesson
• Query the authoritative DNS server directly 11 min read Pro lesson
• Network Performance System Design 11 min read Pro lesson

Module 18: Interview Checklist and Reference

Interview Checklist and Reference - 5 topics.

• Networking Checklist System Design 10 min read Pro lesson
• System Design Networking Dimensions 10 min read Pro lesson
• Networking Tradeoffs 11 min read Pro lesson
• Back Of Envelope Calculations 10 min read Pro lesson
• Networking Vocabulary Reference 11 min read Pro lesson

Browse all courses