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Chapter 3 · Free preview
Networking - The Invisible Highway
What Really Happens When You Click
What you will understand
- Describe the journey of an HTTP request from browser to server
- Explain the difference between TCP and UDP with examples
- Understand how DNS translates a domain name into an IP address
- Explain what ports are and why they matter
- Describe the difference between a process and a thread
Written by EduVerse for this preview; the slides below are the book’s own words.
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Slide 1 of 4
IPv4 vs IPv6: Running Out of Addresses
3.1.2 · p. 65
Conversation from The Software Realm, Decoded
Chapter 3 · 3.1.2 IPv4 vs IPv6: Running Out of Addresses · p. 65
Peter
So we switched to IPv6 in 2011?
Senior developer
We’re still switching. It’s taking forever.
Peter
Why? If IPv4 ran out in 2011, how are we still using it?
Senior developer
Two reasons: NAT and transition pain.
NAT (Network Address Translation): Your home router has one public IPv4 address from your Internet Server Provider (ISP) (Vodafone for instance). But inside your home, you have 10 devices. How?
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Description
Network diagram: three devices, 'Laptop' 192.168.1.5, 'Phone' 192.168.1.6 and 'Tablet' 192.168.1.7, each have an arrow pointing up to a single 'Router' with 'Public IP: 54.239.28.85'.
Description written by EduVerse; the figure itself is from the book.
Senior developer
One public IP, many private IPs behind it. That’s NAT. It bought us time.
DNS: The Internet's Phone Book
3.2 · p. 67
Conversation from The Software Realm, Decoded
Chapter 3 · 3.2 DNS: The Internet's Phone Book · p. 67
Peter
I never type 54.239.28.85. I type google.com. How does my computer know what IP address that is?
Senior developer
DNS. Domain Name System. It’s like a phone book. You give it a name, it gives you a number.
Ports: The Apartment Numbers
3.3 · p. 68
Conversation from The Software Realm, Decoded
Chapter 3 · 3.3 Ports: The Apartment Numbers · p. 68
Peter
But wait. . . the server has just one IP address. It runs a React app, a Spring backend, a database, and Redis. How does my request know where to go?
Senior developer
Great question! This is where a lot of developers get confused at first.
Ports. Think of the IP address as a building’s street address. The port is the apartment number.
What the book shows with it
Figure from The Software Realm, Decoded
Chapter 3 · 3.3.1 Understanding Ports · p. 69
Common ports you’ll use:
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Description
Table: 'Common Ports Overview', listing each 'Port' with its 'Purpose': 80 HTTP websites (unencrypted traffic), 443 HTTPS websites (encrypted traffic), 3000 React development server, 8080 Spring Boot / Java applications, 5432 PostgreSQL database, 3306 MySQL database, 27017 MongoDB database and 6379 Redis cache server.
Description written by EduVerse; the figure itself is from the book.
Putting It All Together: The Complete Journey
3.7 · p. 80
Figure from The Software Realm, Decoded
Chapter 3 · 3.7 Putting It All Together: The Complete Journey · p. 80
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Description
Two-column layer diagram. Left, 'Sending (Encapsulation)': 'Your Browser' creates an HTTP request, 'GET /browse', which moves down through the TCP, IP and Ethernet layers, each step labelled 'wrap', is converted at the 'Physical Layer' and crosses the 'Network'. Right, 'Receiving (Decapsulation)': the same layers 'unwrap' it upward to 'Amazon’s Server'.
Description written by EduVerse; the figure itself is from the book.
Slide 1 of 4
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The full chapter
This preview shows 5 of the chapter’s 46 passages. The full chapter has:
- 8 sections
- 28 conversations
- 3 figures and tables
- 7 What They Say boxes
- 7 knowledge-check questions
Sections in this chapter
- 3.1How Computers Find Each Other: IP Addresses
- 3.2DNS: The Internet's Phone Book
- 3.3Ports: The Apartment Numbers
- 3.4How Data Travels: TCP and UDP
- 3.5HTTP: The Language of the Web
- 3.6Where Data Lives: Memory, Processes, and Threads
- 3.7Putting It All Together: The Complete Journey
- 3.8Peter's Takeaways