Sockets To Satelites

How to Design Internet-Scale Networks

30 modules

122 lessons

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Part 1

Course Setup and the Incremental Ladder

Course Setup and the Incremental LadderSign in
Why Sockets to SatellitesSign in
How to Use This CourseSign in
The Incremental Ladder (Step 0 to Step 7)Sign in
The Course LensesSign in
Diagram Legend and Notation TypesSign in

Part 2

Mental Models: Layers, Paths, and Control

Mental Models: Layers, Paths, and ControlSign in
The Internet as a Layered SystemSign in
Control Plane vs Data PlaneSign in
Reliability Emerges from CompositionSign in

Part 3

Transport & Network Basics (Conceptual)

Transport & Network Basics (Conceptual)Sign in
Sockets, Ports, and ProcessesSign in
TCP vs UDPSign in
IP Packets and MTUSign in

Part 4

Diagramming Networked Systems

Diagramming Networked SystemsSign in
Socket Flow DiagramsSign in
Topology DiagramsSign in
Layer OverlaysSign in

Part 5

Step 0 Endpoints: Local Networking and Simple LANs

Step 0 Endpoints: Local Networking and Simple LANsSign in
Single-Host NetworkingSign in
Simple LANs and Default GatewaysSign in
Basic Address AssignmentSign in

Part 6

Step 0 Transport Realities: Connections in Practice

Step 0 Transport Realities: Connections in PracticeSign in
TCP Lifecycle at a High Level: handshake, teardown, and why TIME_WAIT-ish realities matterSign in
Middlebox Awareness: connection tracking, NAT intuition, and stateful filtering effectsSign in
Timeouts, Retries, and Reuse: correctness under loss, and how apps accidentally DDoS themselvesSign in

Part 7

Step 0 Delivery: Minimal Network for a Service

Step 0 Delivery: Minimal Network for a ServiceSign in
The Minimal Service Network: one host, one service, basic firewall rules, and observability hooksSign in
Failure Surfaces: packet loss, port blocks, MTU weirdness, and "it's always DNS" (eventually)Sign in
Validation in Small: repeatable tests, traffic captures conceptually, and safe change habitsSign in

Part 8

Step 1 Addressing: Subnets and Practical IP Design

Step 1 Addressing: Subnets and Practical IP DesignSign in
Prefixes and Subnets: conceptual masks, allocation, and why IP planning is architectureSign in
Private vs Public Addressing: translation boundaries and where complexity accumulatesSign in
Dual Stack Basics: IPv6 framing, migration posture, and compatibility realitiesSign in

Part 9

Step 1 Layer 2: Switching, VLANs, and Segmentation

Step 1 Layer 2: Switching, VLANs, and SegmentationSign in
MACs and Broadcast Domains: why L2 scales until it doesn'tSign in
VLAN segmentation: separating traffic by purpose, security zone, and operational ownershipSign in
Loop avoidance concepts: spanning-tree-like intuition and failure modes of "just plug it in"Sign in

Part 10

Step 1 Layer 3: Routing Inside an Organization

Step 1 Layer 3: Routing Inside an OrganizationSign in
Routing tables and prefixes: static routes vs dynamic routing families (IGP-level view)Sign in
Default routes and gateways: designing the "exit" and preventing accidental hairpinsSign in
High availability basics: redundant routers, simple failover, and where state bites youSign in

Part 11

Step 1 Delivery: Enterprise LAN/WAN Design Slice

Step 1 Delivery: Enterprise LAN/WAN Design SliceSign in
Core-Distribution-Access: common topology patterns and why hierarchy helps operationsSign in
Zoning by function and risk: prod vs corp, PCI-ish zones, and blast-radius managementSign in
NAT/firewalls as architectural boundaries: what they simplify, what they complicate, and how apps adaptSign in

Part 12

Step 2 DNS Fundamentals

Step 2 DNS FundamentalsSign in
Why Indirection Matters: names as stable handles; IPs as implementation detailsSign in
Recursive vs Authoritative: caching, recursion, and the latency/availability trade spaceSign in
TTLs and Propagation: designing for change without lying to yourself about timeSign in

Part 13

Step 2 Records, Zones, and Architecture Patterns

Step 2 Records, Zones, and Architecture PatternsSign in
Record Types as Primitives: A/AAAA/CNAME/TXT/SRV-like roles conceptuallySign in
Zones and Delegation: scaling ownership across orgs and environmentsSign in
DNS in Application Architecture: multi-record load distribution and DNS-based failover patternsSign in

Part 14

Step 2 Service Discovery Strategies

Step 2 Service Discovery StrategiesSign in
Internal DNS and Split-Horizon Concepts: internal vs external naming, and boundary safetySign in
Naming Conventions at Scale: service/region/env hierarchies that survive re-orgsSign in
When DNS Isn't Enough: dedicated discovery systems conceptually and the cost of "more control"Sign in

Part 15

The Internet as Autonomous Systems

The Internet as Autonomous SystemsSign in
ASNs and the Global Graph: how packets cross many networksSign in
Prefixes and Reachability: why "announcing space" is powerSign in
Failure at the Edges: leaks, misconfigs, and why local mistakes go globalSign in

Part 16

BGP Fundamentals and Policy (Conceptual)

BGP Fundamentals and Policy (Conceptual)Sign in
Sessions and Route Exchange: peers, advertisements, withdrawals at a high levelSign in
Path Selection Intuition: attributes and policy shaping without knob-level depthSign in
Inbound vs Outbound Control: what you can influence, what you mostly can'tSign in

Part 17

Peering, Transit, and Routing Security

Peering, Transit, and Routing SecuritySign in
Peering vs Transit: economic drivers that become topologySign in
IXPs and Peering Fabrics: why shared interconnects change cost and latencySign in
Routing Security Basics: hijacks/leaks, RPKI intuition, and monitoring postureSign in

Part 18

Step 4 Edge Mental Models

Step 4 Edge Mental ModelsSign in
Latency as Geography: why POPs exist and how proximity becomes product qualitySign in
Edge POP Footprints: placement heuristics and failure domainsSign in
Origin Shielding: using edge layers to protect core servicesSign in

Part 19

Step 4 Anycast and Caching

Step 4 Anycast and CachingSign in
Anycast Addressing: one IP, many locations; "nearest" via routing outcomesSign in
Cache Hierarchies: hit rates, parent/child caches, and controlling blast radiusSign in
Invalidation and Freshness: correctness vs cache efficiency as a living tradeSign in

Part 20

Step 4 Beyond Caching: Edge Services

Step 4 Beyond Caching: Edge ServicesSign in
TLS Termination and WAF at the Edge: shifting work outward (and new trust boundaries)Sign in
Edge Compute Concepts: running logic close to users without turning POPs into snowflakesSign in
Multi-CDN Strategies: traffic steering, portability, and operational complexitySign in

Part 21

Step 5 Load Balancing Fundamentals

Step 5 Load Balancing FundamentalsSign in
L4 vs L7 Load Balancing: connection routing vs request routing as different control leversSign in
Health Checks and Out-of-Rotation: truth, lies, and delayed failure detectionSign in
Algorithms and Weights: round robin, least connections, and why "fair" is not always stableSign in

Part 22

Step 5 Global Traffic Steering

Step 5 Global Traffic SteeringSign in
Global Load Balancing Patterns: geo steering, failover, and multi-region postureSign in
Anycast + L7 Steering: combining routing and application logic without fighting yourselfSign in
Session Affinity and State: sticky sessions, stateless design, and mobility of trafficSign in

Part 23

Step 5 Capacity and Failure Engineering

Step 5 Capacity and Failure EngineeringSign in
Traffic Engineering Goals: performance vs cost vs resilience in explicit trade-offsSign in
Load Shedding and Admission Control: graceful degradation at edge and originSign in
Big Event Drills: peak planning, region evacuation patterns, and controlled rollback mindsetsSign in

Part 24

Step 6 Threat Models and Defensive Design

Step 6 Threat Models and Defensive DesignSign in
Attack Classes at a High Level: volumetric, protocol, and application-layer pressuresSign in
Defense-in-Depth Topologies: edge, mid-tier, origin segmentation and blast-radius controlSign in
Flash Crowds vs Attacks: designing systems that survive both without guessing intentSign in

Part 25

Step 6 DDoS Mitigation Building Blocks

Step 6 DDoS Mitigation Building BlocksSign in
Rate Limiting and Filtering: where to enforce, what signals to use, and failure safetySign in
Scrubbing and Diversion: traffic reroute concepts and operational implicationsSign in
Anycast as Absorption: distributing attack load and the debugging complexity it introducesSign in

Part 26

Step 6 Security Operations and Governance

Step 6 Security Operations and GovernanceSign in
Security Telemetry: flows/logs/metrics and the minimum viable situational awarenessSign in
Incident Response for Network Events: runbooks, coordination with providers/peers, and rollback disciplineSign in
Policy and Abuse Handling: enforcement, privacy boundaries, and sustainable operationsSign in

Part 27

Step 7 Long-Haul and Backbone Design (Conceptual)

Step 7 Long-Haul and Backbone Design (Conceptual)Sign in
Metro vs Long-Haul vs Subsea: diversity, latency, and capacity as first-class constraintsSign in
Owning vs Leasing: when control and predictability justify costSign in
Failure Domains at Backbone Scale: link cuts, regional events, and diversity planningSign in

Part 28

Step 7 Satellite and Non-Terrestrial Links (Conceptual)

Step 7 Satellite and Non-Terrestrial Links (Conceptual)Sign in
GEO/MEO/LEO Trade-offs: latency, jitter, handoffs, and link variability as design inputsSign in
Integrating Satellite into Broader Networks: routing posture, backhaul, and service expectationsSign in
Designing for Extreme Latency: timeouts, buffering, and user experience under long RTTsSign in

Part 29

Step 7 Internet-Scale Architecture and Operations

Step 7 Internet-Scale Architecture and OperationsSign in
Regions, POPs, and Backbones: stitching edge and core into coherent failure domainsSign in
Multi-Cloud and Multi-Backbone: hybrid connectivity strategies and observability challengesSign in
Operating Global Networks: NOCs, staged rollouts, change management, and continuous improvement cultureSign in

Part 30

Step 7 Reference Architectures and Maturity

Step 7 Reference Architectures and MaturitySign in
Global SaaS Network: multi-region ingress, edge acceleration, and operational safety railsSign in
Streaming/Video Delivery Network: throughput, caching strategy, and peak-event readinessSign in
Gaming and Global API Platforms: latency sensitivity, routing choices, and fairness under congestionSign in

Course overview