Roles of Computers in a Network
In a networked world, computers take on various roles to ensure seamless communication, data exchange, and resource sharing. Each role is critical to maintaining the functionality and efficiency of networks.
Network
A system where multiple computers or devices (nodes) are connected to share data, resources, and communicate with each other
Such roles include, but are not limited to:
- Client: Enables user interaction with networked services.
- Server: Provides resources and services to multiple clients.
- Email Server: Ensures reliable email communication.
- DNS Server: Simplifies access to online resources by resolving domain names.
- Router: Connects networks and directs data efficiently.
- Firewall: Protects networks from unauthorised access and threats.
Understanding these roles is essential for designing, implementing, and managing networked systems.
Client
Client
A computer or device that requests services or resources from a server
Clients are typically user-facing and rely on servers to provide data and processing power. Clients send requests to servers and receive responses, enabling users to access websites, emails, and other online services.
Web browsers, email applications, and mobile apps can be considered as clients.
If you use a Chromium-based browser, you can right-click Inspect > Network, where you can see all the requests made by the browser to load the page and enable its functionality.
Server
Server
A device or program that provides services or resources to clients
Servers can be dedicated machines or software applications running on general-purpose computers.
Visual explanation Clients vs Servers
The main difference between clients and servers is that servers share their resources, while clients do not.
There are a lot of types of services. Usually, they can be categorised via their main functionality, for example:
- Web Server: Hosts websites and serves web pages to clients.
- Database Server: Manages and provides access to databases.
- File Server: Stores and shares files across a network.
Except server types mentioned above, you have used before email server.
Email server
A server that manages the flow of emails within and outside a network.
It acts as a post office, handling tasks such as sending, receiving, and storing emails.
Key functions of an email server are:
- SMTP (Simple Mail Transfer Protocol): Sends outgoing emails.
- IMAP (Internet Message Access Protocol) / POP3 (Post Office Protocol): Retrieves incoming emails for clients.
Gmail and Outlook use email servers to manage millions of emails daily, ensuring reliable communication for users worldwide.
One of the most important types of servers nowadays is the DNS Server.
Domain Name System (DNS) server
A type of server that translates human-readable domain names (e.g., example.com) into IP addresses (e.g., 192.0.2.1) that computers use to identify each other on the network
Think of a DNS server as a phone book, converting names into phone numbers so you can make a call.
Router
Routers
Routers are devices that direct data packets between networks. They determine the optimal path for data transmission using routing protocols and routing tables.
A router is a networking device that forwards data packets between networks and determines the best path for data to travel based on a routing table or policy.
Key function can be described as:
- Reads destination addresses in data packets.
- Forwards packets to the appropriate network or device.
- Connects different networks, such as a home network, to the internet.
Routers are essential for connecting multiple networks and ensuring data reaches its intended destination efficiently.
Do not confuse a router with a modem or a switch! They are different things!
How to get online: Router vs Modem vs Switch
Firewall
Firewalls
Firewalls are security devices that monitor and control network traffic based on predetermined rules. They act as a barrier between trusted and untrusted networks.
Key functions can be simplified to:
- Monitoring incoming and outgoing traffic.
- Blocking/allowing data packets based on predefined security rules.
- Protecting networks from threats such as hackers and viruses.
- A common misconception is that firewalls make networks completely secure.
- While they provide essential protection, they must be combined with other security measures for comprehensive defence.
The Client-Server Model
Client-server model
A network architecture where clients request services and servers provide them
This model is fundamental to modern computing and underpins many internet and enterprise applications.
A web browser (client) requests a web page from a web server, which processes the request and sends the page back to the browser.
Think of a client as a customer in a restaurant, placing orders (requests) and receiving meals (responses) from the kitchen (server).
At least one server machine is required for the client-server architecture to function.
- Can you explain the difference between a client and a server?
- How does a DNS server contribute to internet functionality?
- Why is a firewall essential for network security?
