1.3 · Network Servers in Practice

Goal: describe the function of each common server type and how they fit together.

The common servers on the syllabus

Server	Role
Web server	Serves HTML, CSS, JS over HTTP(S). Examples: Apache, Nginx
Database server	Stores and queries data. Examples: MySQL, PostgreSQL, SQL Server
File server	Stores shared files for users on the network
Domain controller	Centralises authentication in Windows networks
DHCP server	Hands out IP addresses to clients automatically
Proxy server	Forwards client requests; caches, filters, anonymises
Gateway	Bridges between different protocols or networks

A typical small web app deployment

        Internet
            │
        ┌───┴────┐
        │ Router │
        └───┬────┘
            │
        ┌───┴────────┐
        │ Web Server │ Apache + PHP
        └───┬────────┘
            │
        ┌───┴────────┐
        │  DB Server │ MySQL
        └────────────┘

The web server runs PHP, which connects to MySQL for data.

A typical office network

        Internet
            │
        Router + Firewall
            │
        ┌───┴───────────┐
        │ Switch        │
        ├───┬───┬───┬───┤
       PCs Printer File-srv
                    │
           ┌────────┴────────┐
           │ Domain Controller│
           │   DHCP server    │
           │   File shares    │
           └─────────────────┘

Servers can co-exist on one machine

• A small SBA project may run Apache + MySQL + PHP on the same laptop (LAMP / WAMP / MAMP / XAMPP stack).
• Production usually separates them for scaling and security.

Reverse proxy

A reverse proxy sits in front of one or more web servers, distributing traffic, terminating TLS, and caching responses. Nginx is commonly used this way in front of multiple application servers.

Common student mistakes

• Confusing web server (HTTP) with database server (SQL).
• Calling the web hosting plan "the server" — the server is the software.
• Thinking one machine can host only one server type — it can host many.

Exam-style question

Q (5 marks): A school wants to host a small website with a database backend on its own machine. Describe the servers required and explain why each is needed.

Sample answer:

The school needs three categories of server, all of which can run on one physical machine in a small deployment:

1. Web server (e.g. Apache or Nginx) — receives HTTP requests from students/parents' browsers and serves the website's HTML/CSS/JS, plus executes server-side scripts.
2. Database server (e.g. MySQL) — stores all dynamic content such as student announcements, login credentials, and event sign-ups. The web server's PHP code queries the database server for data.
3. DHCP server / router — provides IP addresses to internal devices so they can reach the web server, and the router NATs the school's public IP to the web server's port 80/443.

For larger deployments, each server can move to its own machine and be load-balanced for performance and resilience.

Key takeaways

• Each server type has a specific job.
• Small projects co-host on one machine; production separates them.
• Understand the path: Browser → Router → Web server → DB server.

➡️ Next: 1.4 Setting up Ethernet / Wi-Fi