Internet and Web Architecture

01

Learning Objectives

Build a strong mental model of how the Internet delivers a web request.

🌍

Internet Architecture

Understand how networks and devices communicate with each other.

📍

IP Addresses

Learn why devices need addresses to communicate.

🔎

DNS

Understand how a domain name is translated into an IP address.

🚪

Port Numbers

Understand how ports help identify network services.

🖥️

Servers

Distinguish web servers, application servers and databases.

🔄

Request Journey

Trace a request from the browser to the server and back again.

02

What Is Internet Architecture?

The Internet is a collection of interconnected networks that communicate using standardized protocols.

The Internet is not one single computer or one giant machine. It is a large collection of interconnected networks that allow devices to exchange data.

A device can communicate with another device through multiple networking components and service providers. Routers help forward packets toward their destination.

When we access a website, several layers work together: the user's device, local network, Internet service provider, DNS services, routers, servers and application software.

💡

Think of the Internet as a road network

Devices are like houses, IP addresses are like addresses, routers are like intersections, and protocols are like agreed traffic rules.

03

Basic Components of Internet Communication

Several components participate in delivering a request.

💻

Client Device

Your computer, laptop, phone or other device that starts a request.

CLIENT

📡

Network

Connects devices and carries data between them.

CONNECTIVITY

🔀

Router

Forwards network packets toward appropriate destinations.

ROUTING

🔎

DNS

Helps map domain names to IP addresses.

NAME RESOLUTION

🖥️

Web Server

Receives web requests and returns resources or responses.

SERVER

⚙️

Application Server

Runs application logic and processes dynamic requests.

PROCESSING

🗄️

Database

Stores persistent application data for later retrieval.

DATA

🏠

Hosting

Provides infrastructure where websites and applications can be made available.

INFRASTRUCTURE

04

What Is an IP Address?

A network address helps identify a device or network interface.

An IP address is a numeric address used in Internet Protocol communication.

A common IPv4 address contains four numeric parts. For example:

203.0.113.25

IPv6 uses a much larger address space and represents addresses using hexadecimal notation.

Remember: A domain name is designed for humans to remember; an IP address is used by networking systems for communication.

05

Public and Private Network Addresses

Addresses can have different scopes depending on where they are used.

🌍

Public IP

Used for communication beyond a private local network.

✔ Used for externally reachable communication

✔ Assigned within an Internet service context

✔ Can identify an Internet-facing endpoint

VS

🏠

Private IP

Used inside a private network such as a home, school or company network.

✔ Used within local networks

✔ Commonly used by routers and local devices

✔ Not directly Internet-routable as a private address

06

DNS — Domain Name System

DNS helps translate human-friendly domain names into addresses used for network communication.

Imagine having to remember a numeric IP address for every website you visit. That would be difficult.

Instead, we use domain names such as:

codebhavya.com

DNS provides the naming system that helps clients find the address associated with a domain name.

01

User enters domain codebhavya.com

↓

02

DNS resolution Domain → network address

↓

03

Browser connects to destination Network communication can begin

07

DNS Resolution — A Little Deeper

DNS is a distributed system rather than one single database.

A

Browser / OS Cache

Previously resolved information may already be available locally for a period of time.

B

Recursive Resolver

A resolver can perform DNS queries on behalf of the client.

C

Root DNS

The root system helps direct queries toward appropriate top-level domain infrastructure.

D

TLD DNS

Top-level domains include systems for extensions such as .com, .org and country-code domains.

E

Authoritative DNS

The authoritative service provides the DNS information for a domain.

F

DNS Record

Records can provide addresses and other information associated with a domain.

Important: DNS can involve several layers of resolution and caching. The complete process is more detailed than a simple “domain directly becomes IP” picture.

08

Understanding a Web Address

A URL identifies the location and access method of a resource.

https://www.codebhavya.com/Web-Technologies/lesson.html?id=2#dns

01

Scheme

https identifies the protocol scheme being used.

02

Host

www.codebhavya.com identifies the destination host.

03

Path

/Web-Technologies/lesson.html identifies the requested resource path.

04

Query

?id=2 carries query parameters.

05

Fragment

#dns identifies a location within the loaded document.

09

Port Numbers

An IP address identifies a network endpoint; ports help identify services at that endpoint.

Port	Common Service	Typical Use
80	HTTP	Traditional HTTP web traffic
443	HTTPS	Encrypted HTTP web traffic
22	SSH	Secure remote administration
25	SMTP	Traditional email transfer
53	DNS	DNS service communication

These terms describe different responsibilities in multi-layer web architectures.

🖥️

Web Server

Commonly handles HTTP requests and serves web resources, and may also act as a reverse proxy.

✔ Static files

✔ HTTP handling

✔ Reverse proxy roles

✔ TLS termination in some deployments

VS

⚙️

Application Server

Commonly executes application code, business rules and dynamic processing.

✔ Business logic

✔ Dynamic responses

✔ Database interaction

✔ Authentication/application services

12

Three-Tier Web Architecture

A common architecture separates presentation, application logic and data.

01

Presentation Layer Browser · HTML · CSS · JavaScript · UI

↓

02

Application / Business Layer PHP · Servlets · JSP · APIs · Business Logic

↓

03

Data Layer Database · JDBC · SQL · Persistent Data

Why separate layers? Separating responsibilities can make applications easier to develop, maintain, secure and scale.

13

Premium Visualizer — From Domain to Database

Trace what happens when a browser requests a dynamic web page.

👤

STEP 01

User Requests a Website

The user enters a domain name in a browser.

https://codebhavya.com

What the tracer teaches

01

DNS helps the client discover where the requested domain should be reached.

02

A request may pass through several network and server components before application processing.

03

The database is normally behind the application layer rather than communicating directly with the browser.

14

Real-World Example — Student Portal

Let's apply the architecture to a college application.

Student Login

A student enters a portal URL and submits a username and password.

The browser sends the request to the appropriate server. The application processes the login information.

The application may query a database and then return a result to the browser.

👨‍🎓 Student

↓

🌐 Browser

↓

🖥️ Web Server

↓

⚙️ Application

↓

🗄️ Student Database

15

Remember These Relationships

These simple connections will help throughout the course.

🌐 Domain

Human-friendly name

📍 IP

Network address

🔎 DNS

Name resolution

🚪 Port

Service endpoint

🖥️ Web Server

Web request handling

⚙️ Application

Business logic

🗄️ Database

Persistent data

🔄 Protocols

A web server commonly handles HTTP traffic and web resources, while an application server commonly executes application logic and dynamic processing. In real deployments, the boundary depends on the architecture and software stack.

Click again to return to the question.

18

Quick MCQs

Check your understanding of Internet architecture.

MCQ 01 EASY

Which system helps translate domain names into network addressing information?

MCQ 02 EASY

Which port is commonly associated with HTTPS?

MCQ 03 MODERATE

Which layer is primarily responsible for business logic in a three-tier application?

MCQ 04 MODERATE

Which component normally stores persistent application data?

19

Practice Problems

Test yourself without referring to the lesson.

01

Explain Internet architecture in your own words.

02

Explain the difference between a domain name and an IP address.

03

Explain the purpose of DNS with a real-world analogy.

04

Explain why an IP address and port number are both useful in network communication.

05

Draw a three-tier architecture for a college student portal.

06

Trace the path of a request from a browser to a database.

20

Quick Revision

The concepts you should remember before Level 03.

🌐 Internet

Interconnected networks

📍 IP Address

Network endpoint address

🔎 DNS

Name resolution system

🚪 Port

Service endpoint

🏠 Hosting

Web infrastructure

🖥️ Web Server

Web request handling

An architecture that separates presentation, application/business logic and data responsibilities.

TERM

Router

Click to see meaning

DEFINITION

Router

A networking device or function that forwards packets toward their destinations.

🎯

Key Takeaway

A web request is part of a larger Internet journey. A browser uses domain names, DNS helps discover addressing information, network communication reaches a server, and the server-side architecture may involve application logic and databases before a response returns to the browser.

This mental model will become extremely important in the next levels when we study URLs, HTTP and HTTPS in detail.