https://www.holbertonschool.com is just the beginning.
It's midnight. You've been thinking about changing your currents life journey. In the news, you took note of a site, something that captured your attention. You reach up to your pocket and take out the paper where you had written the site's address.
You turn your laptop on and open up your browser.
It's 00:03:45 hrs, you click in the search engine filed and type what you had written in your paper address: https://www.holbertonschool.com. Then you just hit Enter.
Your browser is just a user agent, it helps you see the web page your diving into. It retrieves and displays the content you are searching for, nothing else.
So, how does this work?
Your house is connected to what we call the LAN or Local Area Network. The LAN is a limited or small network connection such as your house. This includes your pc, routers, Wi-Fi, ethernet cable connections, and other smaller devices that are connected like your mobile, printers, etc.
Once you type the address and hit Enterthe browser transforms that addressas a query to the internet. A DNS (Domain Name System) recursive resolver will catch the query and transform it into a DNS request. A DNS request has basic information like the address, the time the query was made, the IP (Internet Protocol) address from where the query was sent — your computer — and other information that will help find the content you're trying to reach. DNSs translates domain names to IP addresses. IP addresses are numbers that are hard to memorize to the human brain, for example, 172.16.234.2, but IP addresses are what browsers load to the Internet to get resources.
Every query made to the Internet is under a communication suite protocol. The most common and most used is the TCP/IP or Transmission Control Protocol/Internet Protocol. This protocol is used to interconnect network devices on the internet under a set of rules and procedures. The TCP/IP specifies how the information is going to be transmitted and received throughout the Internet.
The DNS resolver will query a root nameserver and the root server will respond to the resolver with the address of a Top-Level Domain (TLD) DNS server. TLD DNS servers store information of the domains, the domain extensions for example, .com, .net, .org, etc. In our case, you typed a .com extension, so the resolver will lead you to a .com TLD.
Once your query gets out to the Internet is no longer in your LAN (Local Area Network). All of this is happening in the WAN or Wide Area Network. This is where servers are and the Internet is located, or what we know as the “cloud”.
The TLD will respond with the IP address of the holbertonschool.com domain, 34.234.197.104 to the DNS resolver. The DNS resolver will then respond to your browser which then will make a HTTP request to the IP address. HTML stands for Hyper Transfer Protocol and it's used to structure requests and responses throughout the Internet.
The HTTP request to the IP address goes directly to the server where the content will be retrieved via a get request. First it will have to make a small stop into a load balancer. A load balancer is a backend server that distributes incoming traffic and validates that your request is allowed. This means that first, it will check through a firewall that your request was done accessing the correct port. Then the request will be redirected to the less loaded server.
Inside that server you will find with the webserver. The web server is a server that hosts the website static content. This means that the web server stores the HTML, CSS, and JavaScript files that will be sent to your browser to be displayed on your laptops screen.
This server also stores any application server that the website might contain. If can to login to the site with a user name, this is stored inside the server through the application servers in a database. Application servers run software that optimizes databases dynamically inside the servers. For example, if you make any changes or add information to your profile, a POST request is made, instead of a GET request. This will be done automatically. Your computer and the code inside your browser will take care of what kind of request you will make to the website's server.
Remember you only typed https://www.holbertonschool.com?
You made a GET request through the browser. When you typed the address your browser made an HTTP request.
The response you receive from the webserver is an HTTPS response. HTTPS stands for Hypertext Transfer Protocol Secure. It's a protocol backed by SSL certificates. SSL certificates assure that you are receiving encrypted communication between your laptop and the server. This means no one else can interfere in between the communication of your laptop and your computer.
Okay, so guess what? You typed the address at 00:03:45 hrs. Now your clock has 00:04:15 hrs, and your screen looks like this:
Welcome to Holberton School!
