Computer Networks

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What Happens When You Type a URL

The OSI 7-Layer Model

The TCP/IP 4-Layer Model

Packet Structure and Encapsulation

Network Types: LAN, WAN, VPN, and Internet

Interview Questions

Ethernet and Frames

MAC Addresses vs IP Addresses

Switches vs Hubs vs Routers

ARP: How IP Maps to MAC

VLANs and Network Segmentation

Wi-Fi Basics: IEEE 802.11

Interview Questions

IPv4 Addressing and Why It Is Running Out

IPv6: The Replacement

Subnetting and CIDR

How Routing Works

BGP and OSPF for Engineers

ICMP, Ping, and Traceroute

DHCP: How Your Laptop Gets an IP

Interview Questions

TCP vs UDP: When Each Wins

The TCP Three-Way Handshake

TCP Connection Termination

TCP Header Anatomy

Reliability: Sequence Numbers, ACKs, Retransmission

Flow Control & the Sliding Window

Congestion Control: Slow Start, AIMD, Reno, Cubic, BBR

Head-of-Line Blocking

TCP Tuning Knobs in Production

Interview Questions

The DNS Hierarchy

Recursive vs Iterative DNS Resolution

DNS Record Types

DNS Caching and TTLs

Anycast and GeoDNS

DNS over HTTPS and DNS over TLS

Debugging DNS with dig and nslookup

Interview Questions

HTTP Request/Response Anatomy

HTTP Methods and Idempotency

HTTP Status Codes

HTTP/1.1 vs HTTP/2 vs HTTP/3

Persistent Connections, Pipelining, and Multiplexing

HTTP/2 Internals

HTTP/3 and QUIC

TLS Handshake Step-by-Step

Certificates and PKI

HTTP Caching in Browsers, Proxies, and CDNs

Interview Questions

WebSockets: Full-Duplex over a Single Connection

Server-Sent Events (SSE)

Long Polling vs SSE vs WebSockets

gRPC and Protocol Buffers

GraphQL Networking Concerns

MQTT for Lightweight IoT

SMTP, FTP, and SSH: The Older Protocols

Interview Questions

What Is a Socket?

TCP Socket Programming

UDP Socket Programming

Handling Multiple Clients with Threads

Non-Blocking I/O and select()

epoll, kqueue, and IOCP

Async Networking with asyncio and Java NIO

Building a Concurrent TCP Echo Server

Interview Questions

Wireshark Deep Dive

tcpdump for the Command Line

netstat, ss, lsof: Who's Using This Port?

curl and wget Like a Pro

traceroute, mtr, ping: Where Is the Latency?

iperf for Bandwidth Testing

Reading a Packet Capture: A Real Bug

Interview Questions

Latency vs Throughput vs Bandwidth

The Bandwidth-Delay Product

Where Latency Comes From

TCP Optimization in Production

Connection Pooling and Keep-Alive

HTTP Caching Strategies

CDNs and Edge Networks

Finding Network Bottlenecks in Production

Interview Questions

The Eight Fallacies of Distributed Computing

Failure Modes: Timeouts, Partial Failures, Partitions

Retry Strategies and Exponential Backoff

Idempotency: Why Retries Need It

Circuit Breakers

Load Balancing: Layer 4 vs Layer 7

Health Checks and Service Discovery

Graceful Shutdown and Connection Draining

Backpressure and Rate Limiting

Interview Questions

TLS/SSL Deep Dive

Certificate Validation and Common Failures

Common Attacks: MITM, Replay, and Downgrade

DDoS: SYN Floods, Amplification, and Slowloris

DNS Spoofing and Cache Poisoning

Firewalls and IDS/IPS

VPN Protocols: IPsec, WireGuard, and OpenVPN

Zero Trust Networking

Interview Questions

Computer Networks

Welcome

Course Roadmap
Join the Community

Networking Fundamentals

What Happens When You Type a URL
The OSI 7-Layer Model
The TCP/IP 4-Layer Model
Packet Structure and Encapsulation
Network Types: LAN, WAN, VPN, and Internet
Interview Questions

Data Link Layer

Ethernet and Frames
MAC Addresses vs IP Addresses
Switches vs Hubs vs Routers
ARP: How IP Maps to MAC
VLANs and Network Segmentation
Wi-Fi Basics: IEEE 802.11
Interview Questions

Network Layer

IPv4 Addressing and Why It Is Running Out
IPv6: The Replacement
Subnetting and CIDR
How Routing Works
BGP and OSPF for Engineers
NAT and PAT
ICMP, Ping, and Traceroute
DHCP: How Your Laptop Gets an IP
Interview Questions

Transport Layer

TCP vs UDP: When Each Wins
The TCP Three-Way Handshake
TCP Connection Termination
TCP Header Anatomy
Reliability: Sequence Numbers, ACKs, Retransmission
Flow Control & the Sliding Window
Congestion Control: Slow Start, AIMD, Reno, Cubic, BBR
Head-of-Line Blocking
UDP Internals
TCP Tuning Knobs in Production
Interview Questions

DNS

The DNS Hierarchy
Recursive vs Iterative DNS Resolution
DNS Record Types
DNS Caching and TTLs
Anycast and GeoDNS
DNS over HTTPS and DNS over TLS
DNSSEC
Debugging DNS with dig and nslookup
Interview Questions

HTTP and HTTPS

HTTP Request/Response Anatomy
HTTP Methods and Idempotency
HTTP Status Codes
HTTP Headers
HTTP/1.1 vs HTTP/2 vs HTTP/3
Persistent Connections, Pipelining, and Multiplexing
HTTP/2 Internals
HTTP/3 and QUIC
TLS Handshake Step-by-Step
Certificates and PKI
HTTP Caching in Browsers, Proxies, and CDNs
Interview Questions

Modern Application Protocols

WebSockets: Full-Duplex over a Single Connection
Server-Sent Events (SSE)
Long Polling vs SSE vs WebSockets
gRPC and Protocol Buffers
GraphQL Networking Concerns
MQTT for Lightweight IoT
SMTP, FTP, and SSH: The Older Protocols
Interview Questions

Socket Programming

What Is a Socket?
TCP Socket Programming
UDP Socket Programming
Handling Multiple Clients with Threads
Non-Blocking I/O and select()
epoll, kqueue, and IOCP
Async Networking with asyncio and Java NIO
Building a Concurrent TCP Echo Server
Interview Questions

Network Tools and Packet Analysis

Wireshark Deep Dive
tcpdump for the Command Line
netstat, ss, lsof: Who's Using This Port?
curl and wget Like a Pro
traceroute, mtr, ping: Where Is the Latency?
iperf for Bandwidth Testing
Reading a Packet Capture: A Real Bug
Interview Questions

Network Performance

Latency vs Throughput vs Bandwidth
The Bandwidth-Delay Product
Where Latency Comes From
TCP Optimization in Production
Connection Pooling and Keep-Alive
HTTP Caching Strategies
CDNs and Edge Networks
Compression
Finding Network Bottlenecks in Production
Interview Questions

Networking in Distributed Systems

The Eight Fallacies of Distributed Computing
Failure Modes: Timeouts, Partial Failures, Partitions
Retry Strategies and Exponential Backoff
Idempotency: Why Retries Need It
Circuit Breakers
Load Balancing: Layer 4 vs Layer 7
Health Checks and Service Discovery
Graceful Shutdown and Connection Draining
Backpressure and Rate Limiting
Interview Questions

Network Security

TLS/SSL Deep Dive
Certificate Validation and Common Failures
Common Attacks: MITM, Replay, and Downgrade
DDoS: SYN Floods, Amplification, and Slowloris
DNS Spoofing and Cache Poisoning
Firewalls and IDS/IPS
VPN Protocols: IPsec, WireGuard, and OpenVPN
Zero Trust Networking
Interview Questions

Course Roadmap

1 min readUpdated August 14, 2026

13 sections110 chapters

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