Tell the story step by step of how your computer finds the CodeHS server, requests information from the server, and receives it.
Step 1: Domain Name Resolution
When you enter the CodeHS website URL in your computer's web browser, the first step is for your computer to resolve the domain name into an IP address. It does this by sending a request to a Domain Name System (DNS) server. This server looks up the IP address associated with the domain name "codehs.com" and returns it to your computer.
Step 2: Establishing a Connection
Once your computer has obtained the IP address of the CodeHS server, it needs to establish a connection. The computer sends a request to the server's IP address using the Transmission Control Protocol (TCP). The server listens for incoming requests on a specific port.
Step 3: The Server's Response
When the server receives the request from your computer, it processes it and generates a response. The response typically consists of various files and data required to display the CodeHS website. This can include HTML, CSS, JavaScript files, and others.
Step 4: Data Transfer
The server sends the response data back to your computer over the established TCP connection. The data is broken down into small packets, each tagged with an address and sequence number. These packets traverse the internet, passing through routers, until they reach your computer.
Step 5: Reassembling the Data
Once the packets reach your computer, they are reassembled into the original response data by the TCP protocol. This ensures that all the packets are received correctly and in the correct order.
Step 6: Rendering the Website
Once the response data is successfully received, your computer's web browser starts processing it. The browser interprets the HTML, executes any embedded scripts (like JavaScript), applies styles with CSS, and renders the website's content visually.
Step 7: Displaying the Website
Finally, your computer's web browser displays the fully loaded and rendered CodeHS website on your screen. This includes text, images, interactive elements, and any other components that make up the CodeHS user interface.
Throughout these steps, there is a continuous back-and-forth communication between your computer and the CodeHS server to ensure the smooth transfer and display of information.
Step 1: Domain Name System (DNS) Lookup
When you enter the website URL (e.g., codehs.com) into your computer's web browser, the first step is for your computer to find the IP address of the CodeHS server. It does this through a process called DNS lookup.
Step 2: Querying DNS Servers
Your computer first checks its local DNS cache to see if it already has the IP address for CodeHS stored. If not, it sends a DNS query to your Internet Service Provider's (ISP) DNS servers to request the IP address of the server.
Step 3: Recursive DNS Resolution
If the ISP's DNS servers do not have the IP address cached, they start a recursive DNS resolution process. These servers recursively query other authoritative DNS servers, starting from the root servers, to find the IP address of the CodeHS server.
Step 4: DNS Response
After the recursive DNS resolution process, one of the authoritative DNS servers will respond with the IP address of the CodeHS server. This IP address is then sent back to your computer.
Step 5: Setting Up a Connection
Now that your computer knows the IP address of the CodeHS server, it can initiate a connection. It opens a Transmission Control Protocol (TCP) connection to the server's IP address using a specific port (usually port 80 for HTTP).
Step 6: HTTP Request
Once the connection is established, your computer sends an HTTP request to the CodeHS server. This request contains information about what specific resource or information you are requesting, such as a webpage or file.
Step 7: Server Processing
The CodeHS server receives the HTTP request from your computer and processes it. It checks the request, retrieves the requested information or performs the necessary actions, and prepares a response to send back.
Step 8: HTTP Response
The server sends an HTTP response back to your computer. This response includes the requested information or an error message if there was an issue fulfilling the request. The response is typically sent in multiple packets if the data size is larger.
Step 9: Data Transmission
Your computer receives the HTTP response packets from the server. It reassembles the packets into a complete response and checks if any additional packets are needed.
Step 10: Rendering the Page
Once all the response packets are received, your computer's web browser interprets the HTML, CSS, and JavaScript code contained in the response and renders the CodeHS webpage accordingly. This might include displaying text, images, videos, and interactive elements.
The process of finding the CodeHS server, requesting information, and receiving it involves multiple steps across several computer systems and protocols, working together to provide you a seamless browsing experience.
Certainly! Here is a step-by-step explanation of how your computer finds the CodeHS server, requests information, and receives it:
1. Domain Name System (DNS) Lookup: When you type a URL like "codehs.com" into your web browser, your computer starts by performing a DNS lookup. It sends a query to a DNS server, asking for the IP address associated with the domain name "codehs.com."
2. Establishing a TCP Connection: Once your computer obtains the IP address of the CodeHS server, it needs to establish a Transmission Control Protocol (TCP) connection. TCP ensures reliable and ordered delivery of data.
a. 3-Way Handshake: Your computer sends a SYN (synchronize) packet to the CodeHS server, requesting a connection. The server replies with a SYN-ACK (synchronize-acknowledgment) packet, indicating it is willing to establish a connection.
b. Acknowledgment: Finally, your computer sends an ACK (acknowledgment) packet back to the server, confirming the connection is established. Now, your computer and the CodeHS server can communicate.
3. Sending HTTP Request: With the TCP connection established, your computer can now send a Hypertext Transfer Protocol (HTTP) request to the CodeHS server. This request contains specific information about what resource your computer is requesting, such as a webpage or file.
4. Server Processing: The CodeHS server receives the HTTP request and starts processing it. It determines which resource your computer is requesting, performs any necessary calculations or database queries, and generates a response.
5. Sending HTTP Response: Once the CodeHS server has processed the request, it generates an HTTP response. This response typically includes the requested resource (e.g., webpage HTML, file data) along with relevant metadata, such as the response status code.
6. Receiving HTTP Response: Your computer, which has been waiting for the server's response, receives the HTTP response over the established TCP connection. It retrieves the response data and metadata from the received packets.
7. Rendering the Response: Depending on the type of resource requested, your web browser interprets the response. If it's HTML, the browser parses the HTML code, fetches any additional resources (e.g., images, scripts) referenced in the HTML, and renders the webpage on your screen.
That's how your computer finds the CodeHS server, requests information, and receives it. It's a complex process involving DNS lookup, TCP connection establishment, HTTP request/response, and web browser rendering.