joco

🛠️ Web3 Engineer
🎓 @RareSkills_io graduate
🚀 Chains & cities wanderer

[freeCodeCamp.org @freeCodeCamp]

If you want to show that you have a deep understanding of Kubernetes admin, this course is for you.

It'll help you study for (and hopefully pass!) the Kubernetes Administrator Certification exam.

You'll learn about cluster architecture, role-based access control, workloads and scheduling, networking, and lots more.

https://t.co/bABLEwDr4b

[Ayaan 🐧 @twtayaan]

50 YAML commands every DevOps engineer should know.

A handy cheat sheet for Kubernetes, Docker, CI/CD, and Infrastructure as Code.

Save it for later 📌

[Nandkishor @devops_nk]

Most common networking protocol with port:

[freeCodeCamp.org @freeCodeCamp]

Basic web scrapers often break as soon as they hit CAPTCHAs, IP bans, or 403 errors.

In this course, Gavin teaches you how to build production-ready web scrapers that work on modern websites.

You'll use Playwright, Cheerio, residential proxies, and a MERN dashboard to scrape and visualize live data.

https://t.co/okNzAZEIWZ

[Cyber_Racheal @CyberRacheal]

Nmap Commands for Educational Use only.

Nmap is a network scanning tool used by system administrators, IT professionals, and students for security auditing, troubleshooting, and learning.

Common Scans

nmap -sP → Ping Scan: Checks which devices are active on a network.

nmap -sS → TCP SYN Scan: Helps discover open services.

nmap -sU → UDP Scan: Finds active UDP services.

nmap -sV → Version Detection: Identifies service versions for maintenance.

nmap -O → OS Detection: Detects operating system type (for compatibility testing).

nmap -A → Aggressive Scan: Runs multiple checks for detailed results.

Timing & Input

nmap -T4 → Timing Template: Controls scan speed.

nmap -iL → Input from List: Reads targets from a file (useful for admins).

nmap -sn → Host Discovery: Finds devices without scanning ports.

Advanced TCP Techniques

nmap -sX → XMAS Scan: Uses a special test packet to check responses.

nmap -sF → FIN Scan: Uses a different method for host analysis.

nmap -sT → TCP Connect Scan: Connects directly to services.

nmap -sN → Null Scan: Uses empty packets to analyze responses.

nmap -sA → ACK Scan: Helps detect firewall filtering.

Scripting & Port Options

nmap -sC → Default Script Scan: Runs safe built-in scripts.

nmap --script <script> → Run Specific Script: For detailed service checks.

nmap --top-ports <number> → Top Ports Scan: Scans the most used ports.

Note:
These commands are meant for learning, ethical security research, and network administration only. Always use Nmap on your own systems or with proper authorization.

[Elorm Daniel @elormkdaniel]

IP Addressing + DHCP Made EASY!

Every Network Engineer MUST understand these basics before moving to advanced networking concepts!

🔹 In this guide you’ll learn:
✅ Class A, B & C IP Addresses
✅ Private IP Ranges (RFC1918)
✅ DHCP vs Static IP
✅ APIPA Address Explained
✅ Subnet Mask Basics
✅ Real-world device examples

🔸 Quick Reminder:
🔹 DHCP = Automatic IP Assignment
🔹 Static IP = Manual & Fixed Address
🔹 APIPA (169.254.x.x) appears when DHCP fails

👉 Interview Question:
Why are servers usually configured with Static IP addresses instead of DHCP?

📚 Perfect for CCNA, CCNP & IT Beginners
💾 Save this for interview preparation
🔁 Share with networking students

[Dhanian 🗯️ @e_opore]

10 System Design concepts every developer should master:

1. Scalability — design systems that handle increasing traffic and users

2. Load Balancing — distribute traffic across multiple servers efficiently

3. Caching — improve performance by storing frequently accessed data

4. Databases — understand SQL, NoSQL, replication, and sharding

5. Microservices — break applications into independent services

6. Message Queues — enable asynchronous communication between services

7. API Gateway — manage routing, authentication, and rate limiting

8. Fault Tolerance — build systems that continue working during failures

9. Distributed Systems — manage communication across multiple machines

10. Monitoring & Logging — track system health, errors, and performance

Grab the System Design Ebook: https://t.co/WIMretQFPE

[D4rk_Intel @d4rk_intel]

How To Investigate A Telegram Channel, User, or Bot In 2026

Educational OSINT techniques for cybersecurity professionals and threat researchers.

Focus &gt; Public channels, metadata extraction, and ethical investigation frameworks.

#OSINT #CyberSecurity #ThreatIntelligence

[Tom Dörr @tom_doerr]

Interactive Go coding challenges for technical interviews

https://t.co/5BcZJjFoWL

[Ayaan 🐧 @twtayaan]

This GitHub repo might be all you need for DevOps interviews.

100+ real questions
→ Kubernetes
→ Docker
→ Linux
→ CI/CD
→ Networking

Includes video explanations

If you can explain these, you’re ready.

Repo: https://t.co/7x9jRXYyyp

[tut_ml @tut_ml]

Best RAG Tutorials- https://t.co/imhtxSkYvh

[Tom Dörr @tom_doerr]

Curated system design diagrams and concepts for interviews

https://t.co/DdeR6woBTH

[Dhanian 🗯️ @e_opore]

If I had to master API design, I’d learn these concepts:

1. What is an API

2. API Architecture Styles

3. REST Principles

4. RESTful Design

5. GraphQL

6. gRPC

7. SOAP

8. Resource Modeling

9. URI Design

10. HTTP Methods (GET, POST, PUT, PATCH, DELETE)

11. Status Codes

12. Request & Response Structure

13. JSON

14. XML

15. Serialization

16. Deserialization

17. Idempotency

18. Statelessness

19. Versioning Strategies

20. URI Versioning

21. Header Versioning

22. Content Negotiation

23. Pagination

24. Filtering

25. Sorting

26. Searching

27. Rate Limiting

28. Throttling

29. API Gateway

30. Load Balancing

31. Caching Strategies

32. Cache-Control Headers

33. ETags

34. Conditional Requests

35. Authentication

36. Authorization

37. API Keys

38. JWT

39. OAuth 2.0

40. OpenID Connect

41. CORS

42. CSRF Protection

43. Input Validation

44. Data Sanitization

45. Error Handling

46. Error Codes & Messages

47. Logging

48. Monitoring

49. Observability

50. Metrics

51. Tracing

52. Documentation

53. OpenAPI Specification

54. Swagger

55. API Contracts

56. Contract Testing

57. Mock Servers

58. API Testing

59. Postman

60. Load Testing

61. Security Best Practices

62. Encryption (HTTPS/TLS)

63. Secrets Management

64. Rate Limit Headers

65. Webhooks

66. Event-Driven APIs

67. Async APIs

68. Streaming APIs

69. WebSockets

70. Server-Sent Events

71. API Lifecycle Management

72. Deprecation Strategies

73. Backward Compatibility

74. Breaking Changes

75. API Governance

76. Naming Conventions

77. Consistency Rules

78. SDK Generation

79. Developer Experience (DX)

80. API Analytics

81. Usage Tracking

82. Monetization

83. API Marketplace

84. Multi-Tenancy

85. Scalability

86. High Availability

87. Fault Tolerance

88. Circuit Breaker

89. Retry Logic

90. Timeout Handling

91. Service Discovery

92. Microservices Integration

93. BFF (Backend for Frontend)

94. Edge APIs

95. CDN Integration

96. Data Transformation

97. Aggregation Layer

98. Orchestration vs Choreography

(...and more concepts)

===

👋 PS - Want a detailed breakdown of API design best practices?

Read right now:

→ API Design Ebook:
https://t.co/t2KOeauy6O

===

💾 Save this for later & RT to help others learn API design.

👤 Follow @e_opore + turn on notifications.

[Ritesh Roushan @devXritesh]

System Design Series - Day 8/30

API Gateway Patterns – The Front Door of Your Microservices

API Gateway is the single entry point for all your clients.

Without it:
- Mobile/web clients call 10+ different services directly
- Authentication is duplicated everywhere
- Rate limiting, CORS, logging → repeated in every service
- Services are fully exposed to the internet

With it:
- One clean URL for clients
- Centralized auth, rate limiting, routing, aggregation
- Backend services stay hidden and secure

Here’s everything you need to know about API Gateway patterns.

What is an API Gateway?

Think of it as the hotel front desk

Without a front desk:
- Guests wander around looking for rooms
- No security check
- Housekeeping and room service have no coordination

With a front desk:
- Single check-in point
- Routes guests to correct room
- Handles security, coordination, and requests

API Gateway does exactly that for your microservices.

The Problem It Solves

Before API Gateway:

Mobile app needs user profile + orders:
→ Calls User Service directly
→ Calls Order Service directly
→ Calls Payment Service directly

Problems:
- Client knows internal service URLs
- Multiple network calls (slow on mobile)
- Auth tokens sent to every service
- No centralized rate limiting or logging
- Services exposed to the internet

After API Gateway:

Mobile app calls one URL:
https://api.example. com/profile

Gateway handles everything internally:
- Authenticates once
- Routes and aggregates calls
- Returns combined response

Benefits:
- 1 network call from client
- Services completely hidden (security win)
- Centralized cross-cutting concerns
- Much better client experience

Core Responsibilities:
1. Routing
Maps external URLs to internal services
GET /api/users → User Service
GET /api/orders → Order Service

2. Authentication & Authorization
Validates JWT/OAuth once at the gateway.
Services trust the gateway.

3. Rate Limiting
Prevents abuse (e.g., 100 requests/min per user).

4. Request Aggregation
Combines multiple backend calls into one response for the client.

5. Protocol Translation
Client uses REST → Service uses gRPC (handled at gateway).

Advanced Patterns

- Circuit Breaker → Prevents cascading failures when a service is down

- Request/Response Transformation → Convert old → new API formats

- Caching → Cache frequent responses at the gateway level

- Logging & Monitoring → Centralized observability

When to Use API Gateway

Use it when:
- You have multiple microservices
- External clients (mobile, web, third-party)
- You need centralized auth, rate limiting, or aggregation

Don’t use it when:
- Simple monolith (overkill)
- Only internal service-to-service communication
- Ultra-low latency is critical (extra hop)

Popular Solutions

- Kong (open-source, powerful plugins)
- AWS API Gateway (managed, serverless)
- NGINX + Lua (DIY, lightweight)
- Traefik, Envoy, KrakenD

Summary

API Gateway is not just a proxy.

It is the security layer, traffic manager, and aggregator for your entire backend.

It simplifies client code, hides internal complexity, and centralizes cross-cutting concerns.

Trade-offs:
- Extra network hop (adds latency)
- Becomes a critical component (make it highly available)

Used correctly, it’s one of the most valuable pieces in any microservices architecture.

Tomorrow (Day 9): Inter-Service Communication Patterns

Questions about API Gateway?

Drop them below 👇

#SystemDesign #APIGateway #Microservices #Backend

[freeCodeCamp.org @freeCodeCamp]

Database indexes help your queries run much faster.

They let the database find rows without scanning the entire table.

In this article, @Iyiola_dev_ teaches you how indexes work in PostgreSQL with practical examples.

https://t.co/Y5bz7pDnUH

[Vaishnavi @_vmlops]

System Design notes

https://t.co/BTedklDgY6

[Dhanian 🗯️ @e_opore]

Backend Engineering Concepts to Master before Interviews ✅

1. Programming Languages (Python, Java, Node.js, Go)

2. Data Structures & Algorithms (Arrays, Trees, Graphs, Hashing)

3. Object-Oriented Programming (OOP Principles)

4. Functional Programming Basics

5. RESTful API Design

6. GraphQL API Design

7. Authentication & Authorization (JWT, OAuth2, Sessions)

8. Database Fundamentals (SQL vs NoSQL)

9. Relational Databases (PostgreSQL, MySQL)

10. NoSQL Databases (MongoDB, Redis, Cassandra)

11. ORM & Query Optimization

12. Caching Strategies (Redis, Memcached)

13. Message Queues (Kafka, RabbitMQ)

14. Microservices Architecture

15. Monolithic Architecture

16. API Gateway & Load Balancing

17. Concurrency & Multithreading

18. Asynchronous Programming (async/await, event loops)

19. Error Handling & Logging

20. Testing (Unit, Integration, End-to-End)

21. Version Control (Git & Git Workflows)

22. CI/CD Basics for Backend

23. Containerization (Docker)

24. Deployment Strategies (Blue-Green, Canary)

25. Security Best Practices (HTTPS, Encryption, OWASP)

26. Rate Limiting & Throttling

27. System Design Basics (Scalability, Reliability)

28. Observability (Metrics, Logs, Tracing)

29. Cloud Services (AWS, Azure, GCP)

30. Performance Optimization & Profiling

📘 Recommended Ebook for Deep Backend Engineering Mastery
👉 https://t.co/t9mqUuRbjx

[freeCodeCamp.org @freeCodeCamp]

"Trust no one. Verify everything." That's the motto, if you will, of zero-trust authentication.

This approach to security checks every person, every device, and every request – every single time they try to access resources.

In this in-depth guide, @tope_fasasi walks you through implementing zero-trust auth in your web apps.

https://t.co/xHLRBcs4X3

[Nikki Siapno @NikkiSiapno]

15 blogs that will help you become a better engineer:

1. Uber Engineering: https://t.co/KClBA7duej

2. Airbnb Tech Blog: https://t.co/3cxlcGh2Vk

3. OpenAI Engineering: https://t.co/Oo0NcvWKb4

4. AWS Architecture: https://t.co/kvBAMbpyvr

5. Netflix TechBlog: https://t.co/T3StVaZlCB

6. Discord Engineering: https://t.co/ne9lNeUeMX

7. Anthropic Engineering: https://t.co/xnorMy9ISZ

8. NVIDIA Developer: https://t.co/i9y3zNuNyC

9. Slack Engineering: https://t.co/qT1O4xxSoc

10. Cloudflare Blog: https://t.co/oSp5ALRFPT

11. Figma Tech Blog: https://t.co/MQxyVO84Ms

12. Shopify Engineering: https://t.co/U4sptY2tB2

13. Stripe Engineering: https://t.co/w8c7fcJKgj

14. Microsoft Engineering: https://t.co/zgLHpGKBRa

15. GitHub Engineering: https://t.co/83WGnNkagK

Bonus (system design deep dives) Level Up Coding: https://t.co/r3l7NXrMQv

Bonus two: Get our 𝟭𝟰𝟮-𝗽𝗮𝗴𝗲 𝗦𝘆𝘀𝘁𝗲𝗺 𝗗𝗲𝘀𝗶𝗴𝗻 𝗛𝗮𝗻𝗱𝗯𝗼𝗼𝗸 covering 𝟱𝟭 𝘀𝘆𝘀𝘁𝗲𝗺 𝗱𝗲𝘀𝗶𝗴𝗻 𝗰𝗼𝗻𝗰𝗲𝗽𝘁𝘀 for 𝗙𝗥𝗘𝗘 when you join our newsletter. Join 30,001+ engineers: https://t.co/8uVCeyVa1w

What other blogs should be on this list?

🔖 Save for later.
♻️ Repost to help other engineers learn and grow.

[Neo Kim @systemdesignone]

Polling vs WebSocket vs SSE
(explained in 2 mins or less):