Understanding the Client-Server Model
The client-server model is foundational for internet and network interactions. It describes how devices (clients) request services from servers, which fulfill these requests.
Using a web browser and a YouTube server as an example, my aim is to explain the process from initiating a request to receiving a response.
The Client-Server Model
When you want to watch a video on YouTube, your browser (the client) requests the video, and YouTube's server (the server) processes this request and sends back the video.
How DNS Connects Clients to Servers
Initially, your browser does not know the server's location. The Domain Name System (DNS) resolves this by translating youtube.com into an IP address, which is a unique identifier for the server. DNS acts like a phonebook, converting domain names into IP addresses so your browser can find and communicate with the YouTube server.
IP Addresses and Communication
An IP address is a unique set of numbers assigned to each device on the internet. It functions like a postal address, ensuring information sent over the internet reaches the correct destination.
After DNS resolution, your browser uses the IP address to connect to the server.
HTTP Requests and Port Numbers
To request a video, your browser sends an HTTP (HyperText Transfer Protocol) request to the server. HTTP is a set of rules for transmitting files on the web.
However, an IP address alone is not enough because a server can run multiple services. Port numbers specify the service you want to access. For web traffic, common port numbers include 80 for HTTP and 443 for HTTPS, directing your request to the server's web service.
Visualization
Summary
The client-server model is the foundation of internet communication. It starts with a domain name, then uses DNS to find the server's IP address, and sends an HTTP request to a certain port number. This process makes sure your requests are handled correctly and you get responses, allowing you to use and interact with web services.