RAHUL SAI

VPN also known as a Virtual Private Network, this is used to establish a secure connection over the internet. By using the VPN we can surf over the web anonymously and our data will travel in encrypted form so that our data is not intercepted by other people. Why we use a VPN? Let us consider a situation, you are somewhere in a public place and you are connected to public Wi-Fi, Imagine you are entering a website and you want to enter sensitive data like your username and password, If any hacker connected to that public Wi-Fi then he can intercept all data what you are entering since you and the hacker are connected to the same Wi-Fi. So here if we use a VPN, our connection becomes private and the hacker will not be able to get our data since it will be in the encrypted form. How does a VPN work? Usually, the working flow of connecting to a web application is: In the browser we will enter the domain name --- Using the DNS this domain name converts into an IP address --- It goes to ISP

Let's first understand what is hacking. Hacking in simple terms, it is a process of breaking into something without the permission of the real owner. The person who does hacking is called a hacker. How a hacker can gain access to a system:   i)   Through Front door   ii)   Backdoors iii) Trojan Horse   iv) Software vulnerability exploitation We will go through each topic   à Front door: In this, the hacker will be guessing our passwords or he/she tries to crack the password using different tools and techniques.   à Backdoor:   These are often left by developers to debug or fix any error in their software, some security measures will be there to gain administrative access to that software, but our hackers will find these backdoors in the software and they will bypass these security measures and gain access.   There are 2 types of backdoors:    Administrative backdoors : These are set by the developers so that they can easily reach and rectify the problems

  The abbreviation of an API is "Application Programming Interface". Many developers use APIs in their applications to enhance the working of their applications because without writing any complex codes they can use that various kinds of services through APIs. We don't know how it is made but we can use all its features(the final product) a simple example we can consider is any food item we don't know how it is made but we enjoy the final product. Let's take a small example, you often visit so many websites and you can see there will be a 'sign up' option when you click it you may able to see some options like 'sign in with google' or 'sign in with Twitter' or 'sign in with Facebook' , etc, so what happens back there when you click that, does the application directly interacts with google or any company servers? No absolutely not this is where the APIs come into the picture, API's will act like a mediator between the serve

  DNS-Domain Name System is a system that translates website names to IP addresses.   As you can see in the above picture we have taken a website "www.rahulsai.com" so now the following steps will describe how DNS works internally. 1. We will enter a website in our web browser, here we took "www.rahulsai.com" 2. Now this website will go to the ISP(Internet Service Provider) from ISP it will go to the DNS resolver. Here the resolver will be operated by the ISP. So now this will start looking at the website name in its local cache if it is found then it will return to the web browser. 3. If the website is not found in the local cache then the resolver sends the request to the "ROOT SERVER". The root server will be checking the TLD(Top Level Domain) of the website. Note1: There are a total of 13 root servers across the globe. Note2: TLD-Top level Domain are .com, .dev, .org, etc which come after the domain name and are known as TLD. For ex: www.

Ever imagined how a webpage is loading when we just enter that site name. Here I am gonna tell you how that works actually. Let's take an example website say 'www.abcd.com' , here "abcd" is called the domain name.  We will be having a system called 'Domain name System' which helps to translate domain names to IP addresses. So, first, when we type a website in our browser, our browser sends the request to the DNS server, and the DNS server gives the IP address of that website to our browser, now that IP address points to the respective server and gathers all required files for website loading and again it gives to the browser and at last, the browser will display us the webpage. In the above picture as we can see a website name 'www.abcd.com'. The following steps were done to load the webpage. User searches for 'www.abcd.com' in the web browser. The browser sends the website name to the 'DNS server' and requests it to give the IP add