Networking

A computer network is a group of connected devices (called nodes) that can communicate and share resources like files, printers, or the internet.

Nodes

Nodes can include:

  • Personal computers

  • Servers

  • Networking hardware (like routers and switches)

  • Specialized devices (like smart TVs or printers)

Example:
A home network might connect your laptop, phone, and Wi-Fi router so you can browse the internet or stream videos.

Network Addresses

Each node has a network address used to identify and locate it within the network.
These addresses are used by communication protocols such as the Internet Protocol (IP).

Example:
Your computer might have an IP address like 192.168.1.10, which helps other devices send data to it.

Hostnames

A hostname is a human-readable name for a device on the network. It’s easier to remember than a numeric address and rarely changes once set.

Example:
Instead of using the IP 192.168.1.10, your laptop might be called Harrison-Laptop on the network.


A computer network connects different devices so they can talk to each other.
Each device has:

  • A network address (its “street address”)

  • A hostname (its “nickname”


A network host is any computer or device connected to a network.

  • It could be a PC, laptop, phone, printer, server, or router.

  • If it’s on the network and can send/receive data, it’s a host.

Example:
Your laptop connected to Wi-Fi is a host.
A printer on the same network is also a host.

A host can:

  • Provide services (like a web server or file server)

  • Offer applications (like a game server or mail server)

  • Use services from other hosts



So a host can be both a client (asking for stuff) and a server (giving stuff).

Example:

A web server is a host that gives web pages.
Your phone is a host that requests those pages.



Every host is assigned at least one network address so other devices can find it.

Example:
A host might have an IP address like 10.0.0.25.

If the network uses the Internet Protocol (IP), the device can be called an IP host.

  • If it’s actually on the Internet, it’s called an Internet host.

  • These hosts have one or more IP addresses assigned to their network interfaces (like Ethernet or Wi-Fi).

Example:
A home PC with Wi-Fi and Ethernet might have two IPs — one for Wi-Fi, one for Ethernet.

How Do Hosts Get Their IP Address?

IP addresses can be set in different ways:

  1. Manually – an admin types it in (called static IP).

    • Example: A server is given the fixed address 192.168.1.50.

  2. Automatically with DHCP – the network’s DHCP server gives the host an IP when it connects.

    • Example: Your phone joins Wi-Fi and gets 192.168.1.23 automatically.

  3. Stateless autoconfiguration (mostly in IPv6) – the host creates its own address based on the network’s prefix.

Resource

  • Could be a:

    • File

    • Video

    • Image

Servers

A server is a computer or device that provides a service or shares resources with other devices on the network.
It “serves” data, files, or applications to clients.

Example:


A web server sends web pages to your browser.

A file server stores and shares documents with multiple users.

Clients

A client is a device or program that requests services or resources from a server.
It’s the one that “asks” for data.

Examples:


A phone using a web browser to open a website (it’s the client asking the server for the page).


A laptop connecting to a file server to download a document.

Servers in Data Centers

Servers used in data centers (like those for Amazon or YouTube) are very powerful computers designed to handle many users at once.

Key Features:

  • High CPU power – so they can process many requests quickly.

  • Large amounts of RAM – to keep data ready for fast access.

  • Huge storage space – to hold videos, files, and other resources for millions of users.

Example:
YouTube’s servers store and stream videos to millions of viewers around the world every second.

Clients Accessing Servers

Many client devices (phones, laptops, tablets, etc.) connect to these servers to access the services or resources they provide.

  • The client requests the resource (like a YouTube video).

  • The server delivers it.

Examples:


Downloading a document → your laptop is the client, and the file server provides the file.


Watching a YouTube video → your phone is the client, YouTube’s data center is the server.

Servers Aren’t Always Big Machines

A server doesn’t have to be large or stored in a data center.
Any computer that provides resources or services to another can act as a server.

Example:


When your laptop shares files over your home Wi-Fi, it’s acting as a server.


When it downloads files from another device, it’s acting as a client.

Connecting Devices Using IP Addresses

When one device (like a phone) connects to another (like a laptop), it can use the laptop’s IP address to communicate directly over the same network.

Example:
If your laptop’s IP address is 192.168.0.21, your phone can connect to it through that address — as long as both are on the same Wi-Fi network.

What Happens When You Connect

When you connect your phone to Wi-Fi, your router assigns it an IP address using DHCP (Dynamic Host Configuration Protocol).
Each device on that Wi-Fi network will get a unique IP address, so they can communicate without confusion.

Example:

Laptop: 192.168.0.21


Phone: 192.168.0.22
Your phone can now access resources (like shared files or web pages) hosted on your laptop.


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