Networking Tutorial for Beginners

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in this tutorial we’re going to take a look at computer networking and how networks work from beginning all the way to the end now there are two primary ways to connect to the Internet

one of course is through your computer and the other of course is through your mobile phone and you can see here I’ve got two main portions to this one is of course the Internet and then I have a

distributed network over here that represents a company’s website that you might connect to so let’s start from beginning all the way to the end so if you’re over here on your computer and

you type in HTTP now HTTP is the protocol that is used to communicate back and forth from your computer to a web server and then of course from the web server back to your computer now

when you attempt to connect to a web server that is called a request the message that gets sent back is called the response so that is going on when you open up your browser and you type in

HTTP and the web address that you want to go to now when you first make that request you will hit your local ISP now it used to be that the major ISP and the local ISP were different companies but

today those local ISPs have been bought out by the big ISPs so it’s not uncommon for these to be the same company so once again you’ll hit this local ISP then before you get to the major ISP you will

go through several third-party cloud devices as well as several content delivery networks then eventually your packet will eventually make it to the major ISP and then the major ISP will

redirect it to the website that you are intending to reach now you’ll notice this big brick wall here this represents a firewall and companies will put up firewalls to protect themselves from the

internet so they will only accept certain types of requests that come from your computer the packet has to be correct with the correct port and IP address and we’ll talk more about that

actually in the next video how packets work so anyways if everything is correct you will be allowed through this firewall think of this almost like a gatekeeper from

medieval times a gatekeeper will allow only certain people to enter into the castle he will reject everybody else that does not have the proper credentials so once you are accepted

through the firewall you will hit the web server now this is a very important server obviously because this hosts the landing page or the homepage this is what you see

when you hit the company’s web server now I do want to point out that in very large companies they will often have all kinds of load balancers switches and routers before you even hit the

webserver so once the webserver does whatever it needs to it ships it off to an application server now an application server is a web server but usually does

not actually host out the landing page or home page that is what the main web server does the application server will handle the communications to the database server that’s one of its

primary functions and then whatever data needs to be stored will be done by the database server and let’s say you made some sort of configuration change and let’s say you were setting up some stock

symbols that you wanted to watch and he wanted to have some alerts set up that would be stored on physical storage and this is actually the lowest level in this entire chain and then the response

would be sent from the web server back to your screen so this entire process from request to response is called the roundtrip that’s what you’ll hear Network professionals call this the

round-trip now I also want to point out something else that is used inside the distributed network you will hear people often call this this layer right here they will refer to as the front-end tear

that is because this is at the front line again this is the landing page or home page that you see so they will refer to this layer as the front-end tier it is also called the presentation

tier now this tier the application server is often called the middle tier or logic tier now at the database level this is often called the backend tier or data tier so this is the lowest level

now why is this important well a lot of web programmers will refer to this when they’re developing their web application they may say hey we’re working on the front tier or we’re working on the

middle tier or we’re working on the lower level tier the other important note I want to make here is you’ll hear these buzzwords today called application performance monitoring and that is

becoming more and more important and what does that mean well companies are very concerned about that round-trip from your client to their web servers and how long that takes so that’s called

application performance monitoring and basically you know when you’ve been on the web and the page doesn’t load that is a performance issue and so they want to know what is causing that is

on your PC is it out in the internet or is it within their own distributed network and so if that slowdown is inside their distributed network they want to know where that slowdown is

occurring is it occurring in the front end tier or is it a problem in the low end here so that’s becoming very critical companies are more and more concerned how their application is

performing and how long that round-trip takes from your client to the web server okay that’s going to do it for this video thank you