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ISPs and the Tiered ISP Hierarchy (Tier 1, 2, 3)
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Introduction to the CourseWhat Is the Internet? A Big-Picture OverviewBrief History: From ARPANET to the Modern InternetHow Data Travels from Your Device to a Server Across the WorldPhysical Infrastructure: Undersea Cables, Data Centers, and IXPsISPs and the Tiered ISP Hierarchy (Tier 1, 2, 3)Last-Mile Connectivity: Fiber, DSL, Cable, CellularWho Owns the Internet? Why No Single Entity Owns ItPeering Agreements and Content Delivery Networks (CDNs)Who Governs the Internet? ICANN, IANA, IETF ExplainedRegional Internet Registries: ARIN, RIPE NCC, APNIC, LACNIC, AFRINICW3C, IEEE, and ITU: Complementary Standards BodiesHow a Web Request Actually Works: End-to-End WalkthroughPractical: Tracing a Request with Browser Developer ToolsQuiz, Homework and HandoutsTerminal Demo: Network Diagnostics
What Is a Computer Network? Definition and Purpose
Client-Server vs Peer-to-Peer Architecture
Types of Networks: PAN, LAN, MAN, WAN, CAN, SAN
Real-World Examples of Each Network Type
Network Topologies: Bus, Star, Ring, Mesh, Hybrid, Tree
Physical vs Logical Topologies
Networking Devices: Hub, Switch, Router, Modem
Access Point, Bridge, Gateway, Repeater
Firewall, Load Balancer, Proxy Server Explained
How Each Device Operates at Different OSI Layers
Transmission Media: Ethernet Cables (Cat5e, Cat6, Cat6a, Cat8)
Fiber Optic: Single-Mode vs Multi-Mode
Coaxial Cable and When to Use Each
Wireless Media: Wi-Fi, Bluetooth, Infrared, Cellular
Network Interface Cards (NICs) and MAC Addresses
MAC Address Format: How to Find Yours
MAC vs IP Address: Understanding the Difference
Quiz, Homework and Handouts
Introduction to the OSI Model: Why Layered Models Exist
Encapsulation and De-Encapsulation Explained
PDUs at Each Layer: Data, Segments, Packets, Frames, Bits
Layer 1 - Physical Layer: Signals, Cables, Hubs, Repeaters
Layer 2 - Data Link Layer: Frames, MAC Addressing, Error Detection
Layer 2 Deep Dive: Switches, Bridges, and ARP Protocol
Layer 2 Sublayers: LLC and MAC Explained
Practical: How a Switch Forwards Traffic Within a LAN
Layer 3 - Network Layer: IP Addressing and Routing
Layer 3 Deep Dive: Routers, ICMP, and Forwarding Decisions
Practical: How a Packet Finds Its Way Across the Internet
Layer 4 - Transport Layer: TCP vs UDP
Layer 4 Deep Dive: Ports, Sockets, Multiplexing, Segmentation
Practical: Why Streaming Uses UDP and Banking Uses TCP
Layer 5 - Session Layer: Session Establishment and Teardown
Layer 6 - Presentation Layer: Encryption, SSL/TLS, Encoding
Layer 7 - Application Layer: HTTP, FTP, SMTP, DNS, SNMP
Full Packet Walkthrough: Tracing an Email Through All 7 Layers
OSI Model Recap and Common Interview Questions
Quiz, Homework and Handouts
TCP/IP Model Overview: The 4 Layers
TCP/IP vs OSI Model: Why TCP/IP Won in Practice
Mapping OSI Layers to TCP/IP Layers
TCP Deep Dive: Header Structure and Reliability Mechanisms
TCP Sliding Window, Flow Control, and Congestion Control
The TCP Three-Way Handshake: SYN, SYN-ACK, ACK
TCP Connection Teardown: FIN and FIN-ACK
Practical: Capturing a Handshake in Wireshark
UDP Deep Dive: Header Structure and Minimal Overhead
UDP Use Cases: DNS, Video Streaming, Gaming, VoIP
TCP vs UDP: Complete Side-by-Side Comparison
Choosing the Right Protocol for Your Application
Ports and Sockets: Well-Known, Registered, Ephemeral
Common Port Numbers: HTTP 80, HTTPS 443, SSH 22, FTP 21, DNS 53
What Is a Socket? (IP + Port Combination)
Practical: Checking Open Ports on Your Machine
Quiz, Homework and Handouts
Introduction to IP Addressing: What and Why
Binary Number System Refresher for Subnetting
Converting Between Binary and Decimal
IPv4 Address Structure: 32-Bit, Dotted Decimal
Network Portion vs Host Portion
Subnet Mask and Its Role
IPv4 Address Classes: A, B, C, D, E Explained
Default Subnet Masks for Each Class
Why Classful Addressing Is Obsolete (But Still Tested)
Public vs Private IP Addresses
Private Ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
Loopback (127.0.0.1), APIPA (169.254.x.x), Link-Local
How to Find Your Public IP vs Private IP
Subnetting: Why It Exists and How It Works
Calculating Subnets Step by Step
Finding Network Address, Broadcast Address, Usable Hosts
Subnetting Practice: 10 Worked Examples
CIDR (Classless Inter-Domain Routing) Notation
Supernetting and Route Aggregation
VLSM (Variable Length Subnet Masking)
Practical: Designing a Subnet Scheme for a Small Business
IPv6: Why It Exists (IPv4 Address Exhaustion)
IPv6 Address Structure: 128-Bit, Hexadecimal Notation
IPv6 Address Types: Unicast, Multicast, Anycast, Link-Local
IPv6 Header Simplification vs IPv4
Dual-Stack, Tunneling, and Transition Mechanisms
IPv4 vs IPv6: Complete Comparison
NAT: How Private IPs Access the Internet
Static NAT, Dynamic NAT, PAT (Port Address Translation)
NAT Traversal Challenges
Practical: Your Home Router Performing PAT
Quiz, Homework and Handouts
What Is DNS and Why It Exists
DNS Hierarchy: Root Servers (13 Logical Groups)
TLDs: Generic (.com, .org), Country-Code (.pk, .uk), New gTLDs (.dev)
Authoritative Name Servers vs Recursive Resolvers
DNS Zones and Delegation
How a DNS Query Works Step by Step
Recursive vs Iterative Queries
DNS Caching: Browser, OS, Resolver Cache
TTL (Time to Live) and Its Significance
Full Walkthrough: Resolving www.example.com
DNS Record Types: A, AAAA, CNAME, MX, NS
DNS Record Types: TXT (SPF, DKIM, DMARC), SRV, SOA, PTR
Real-World Usage of Each Record Type
DNS Propagation: Why Changes Take Time
DNSSEC: Securing DNS Against Spoofing
DNS over HTTPS (DoH) and DNS over TLS (DoT)
Public DNS: Google 8.8.8.8, Cloudflare 1.1.1.1, Quad9
Practical: Using nslookup and dig to Query DNS
Quiz, Homework and Handouts
DHCP: The DORA Process (Discover, Offer, Request, Acknowledge)
DHCP Lease, Renewal, and Release
DHCP Relay Agents for Multi-Subnet Environments
Static IP vs DHCP: When to Use Each
HTTP Methods: GET, POST, PUT, PATCH, DELETE
HTTP Status Codes: 2xx, 3xx, 4xx, 5xx Explained
HTTP Headers, Cookies, and Sessions
HTTPS = HTTP + TLS: How Encryption Secures Web Traffic
HTTP/1.1 vs HTTP/2 vs HTTP/3 (QUIC)
FTP Active vs Passive Mode
Why FTP Is Insecure: SFTP and FTPS Alternatives
SSH: How It Works, Key Exchange, Encryption
SSH Password vs Key-Based Authentication
SSH Tunneling and Port Forwarding
Practical: Connecting to a Remote Linux Server via SSH
Email Protocols: SMTP (Sending), POP3 (Downloading), IMAP (Syncing)
How an Email Travels from Sender to Recipient
SNMP: Network Monitoring Protocol
NTP: Time Synchronization Across Networks
LDAP: Directory Services and Authentication
RDP: Remote Desktop Protocol
Telnet: Why It Is Deprecated
Practical: Using curl, wget, ssh in Real Scenarios
Quiz, Homework and Handouts
Switching Fundamentals: How a Switch Learns MAC Addresses
MAC Address Table: Unicast Flooding, Broadcast, Multicast
Managed vs Unmanaged Switches
ToR (Top-of-Rack) Switches in Data Centers
VLANs: What They Are and Why They Matter
Creating VLANs: Separating HR, Engineering, Guest Networks
Trunk Ports and Access Ports
802.1Q VLAN Tagging
Inter-VLAN Routing: Router-on-a-Stick Method
Inter-VLAN Routing: Layer 3 Switch Method
Spanning Tree Protocol (STP): Why Layer 2 Loops Are Dangerous
How STP Prevents Broadcast Storms
Root Bridge Election Process
RSTP (Rapid Spanning Tree Protocol)
Routing Fundamentals: What a Routing Table Is
How Routers Make Forwarding Decisions (Longest Prefix Match)
Default Gateway Explained
Static Routing: Configuration and Use Cases
Dynamic Routing Overview: Distance-Vector vs Link-State vs Path-Vector
Interior vs Exterior Gateway Protocols (IGP vs EGP)
Administrative Distance
RIP (Routing Information Protocol): Basics and Limitations
OSPF: Link-State Protocol and Dijkstra's Algorithm
OSPF Areas, Area 0 Backbone, ABRs
OSPF Hello Packets, Neighbor Adjacency, LSAs
BGP: The Routing Protocol of the Internet
eBGP vs iBGP and Autonomous Systems
BGP Path Selection Attributes
Real-World: How ISPs Exchange Routes via BGP
Notable BGP Incidents: Route Leaks and Hijacking
HSRP and VRRP: First-Hop Redundancy Protocols
Link Aggregation: EtherChannel / LACP
Network Redundancy and Failover Strategies
Quiz, Homework and Handouts
Network Security Fundamentals: CIA Triad
Defense in Depth Strategy
The Principle of Least Privilege
Firewalls: Packet Filtering, Stateful Inspection, Application-Layer
Hardware vs Software Firewalls
Firewall Rules and ACLs (Access Control Lists)
Next-Generation Firewalls (NGFW)
DMZ (Demilitarized Zone) Architecture
Practical: Configuring iptables Firewall Rules
VPN: What It Does and How It Works
Site-to-Site VPN vs Remote-Access VPN
IPSec (IKE, ESP, AH) vs SSL VPN
WireGuard and Modern VPN Protocols
Split Tunneling vs Full Tunneling
SSL/TLS: Symmetric vs Asymmetric Encryption
The TLS Handshake Step by Step
Certificates, Certificate Authorities, and Chain of Trust
TLS 1.2 vs TLS 1.3 Improvements
DDoS Attacks: Volumetric, Protocol, and Application Layer
Man-in-the-Middle (MITM) Attacks
ARP Spoofing / ARP Poisoning
DNS Spoofing and Cache Poisoning
Phishing, Social Engineering, and Port Scanning
IDS vs IPS: Detection vs Prevention
Signature-Based vs Anomaly-Based Detection
Network-Based (NIDS/NIPS) vs Host-Based (HIDS/HIPS)
Tools: Snort and Suricata
SIEM (Security Information and Event Management)
802.1X Port-Based Authentication
RADIUS and TACACS+
Zero Trust Network Architecture (ZTNA)
Quiz, Homework and Handouts
How Wi-Fi Works: Radio Frequencies and Channels
2.4 GHz vs 5 GHz vs 6 GHz (Wi-Fi 6E)
Wi-Fi Standards: 802.11a/b/g/n/ac/ax (Wi-Fi 4/5/6/6E)
SSIDs, BSSIDs, and ESSIDs
Wireless Security: WEP (Broken), WPA, WPA2, WPA3
PSK vs Enterprise (802.1X/RADIUS)
Common Wireless Attacks: Evil Twin, Deauth, Wardriving
Best Practices for Securing a Wireless Network
Site Surveys and Heat Maps
Access Point Placement and Channel Planning
Controller-Based Architectures and Mesh Networking
Bluetooth Basics and Use Cases
NFC: Contactless Payments and Pairing
Cellular Networking: 4G LTE and 5G
IoT and Wireless Sensor Networks
Quiz, Homework and Handouts
Troubleshooting Methodology: OSI-Based Approach
Structured Problem-Solving: Identify, Test, Implement, Verify
ping and ICMP: Echo Request / Echo Reply
Reading ping Output: TTL, Latency, Packet Loss
Common ping Scenarios: Unreachable, Timed Out
traceroute / tracert: Mapping the Packet Path
Reading traceroute Output and Identifying Bottlenecks
MTR: Combining ping and traceroute
netstat and ss: Viewing Active Connections and Ports
lsof -i: Process-to-Port Mapping
nslookup and dig: Querying DNS Records Manually
Diagnosing DNS Resolution Failures
Wireshark: Installing and Setting Up
Wireshark: Capturing Packets and Using Filters
Wireshark: Analyzing TCP Handshake and HTTP Requests
Wireshark: Identifying Anomalies and Suspicious Traffic
tcpdump: Command-Line Packet Capture
ipconfig / ifconfig / ip addr: Viewing Network Config
arp -a, route / ip route: ARP and Routing Tables
curl, wget: Testing HTTP Endpoints
iperf: Bandwidth Testing Between Two Points
Scenario: I Can't Access the Internet (Systematic Diagnosis)
Scenario: The Website Is Slow (DNS, Routing, or Server?)
Scenario: VLANs Can't Communicate (Inter-VLAN Troubleshooting)
Quiz, Homework and Handouts
Cloud Computing and Networking: IaaS, PaaS, SaaS
Virtual Private Cloud (VPC) / Virtual Network (VNet)
Subnets, Route Tables, and Internet Gateways in Cloud
Security Groups and Network ACLs (Cloud Firewalls)
Elastic IPs and Public IP Allocation
Load Balancers: ALB, NLB, CLB
CDN: CloudFront, Cloudflare, Azure CDN, HostupCloud CDN
Cloud DNS: Route 53, Azure DNS, Cloud DNS, HostupCloud DNS
VPN and Direct Connect / ExpressRoute
Docker Networking: Bridge, Host, Overlay
Kubernetes Networking: Pods, Services, Ingress
Service Mesh: Istio and Envoy
Software-Defined Networking (SDN)
SD-WAN for Enterprise Wide-Area Networking
Network Functions Virtualization (NFV)
Quiz, Homework and Handouts
Top 50 Networking Interview Questions Explained
Subnetting Speed Drills: 20 Rapid-Fire Problems
Scenario: User Cannot Access Intranet (Walkthrough)
Scenario: Design a Network for a 200-Person Office
Scenario: What Happens When You Type google.com?
Scenario: Secure a Network with No Firewall
Protocol and Port Number Quick Reference Guide
CompTIA Network+ Exam Overview and Study Tips
Cisco CCNA Overview and Study Tips
AWS/Azure/HostupCloud Network Engineer Certifications
Quiz, Homework and Handouts
Full Course Recap: Key Takeaways by Module
Networking Cheat Sheet: OSI, Ports, Subnetting, CLI Commands
Building Your Home Lab: GNS3, Packet Tracer, VirtualBox
Career Paths: Network Admin, Engineer, Security, Cloud Networking
Recommended Resources and What to Learn Next