Great guide on computer LANs, internet and wifi

Computer networks, those that connect computers to each other and allow our PCs and mobile phones to connect to the internet and browse websites, are now quite simple to configure, even if there is enormous complexity behind them.
The intention of this guide to LAN networks, Wifi and internet connection however, it is not to provide a manual to pass the exam at the university, but much more humbly to provide a vademecum with the most important notions not only to understand something more theoretically, but above all to understand how the connections are made and how to resolve any connectivity issues that may arise.
Having already written numerous articles about it, we can consider this as one great guide on home computer network and internet, a summary or a front page to start with to find more accurate instructions on every aspect.

1) The internet access device today is the router
Even if it is possible to surf the internet without a router, through direct computer access to the modem, it is not possible to create a LAN or a Wifi network without a router.
In this regard it is important to know the differences between router and modem and above all to understand what a router really does.
In summary, the modem is that device that connects to the internet, that is to the whole network of devices that manage websites and applications.
The router, on the other hand, serves to direct the data received from the outside to the right computer.
In other words, if the modem is the door to leave the house, the router is, instead, like a policeman who tells the data to go one way or the other.
Usually the router and the modem are in the same device we have at home, the one with the lights that connects to the wall at the telephone socket.

2) How network devices on the internet communicate
From a theoretical point of view, the data that is sent and received by a computer via the internet is managed by the TCP / IP protocol.
We have explained how this works in the guide on how TCP / IP works and how computers on a network speak.
Generally speaking, while the Transmission Control Protocol (TCP) is responsible for breaking down data into small packets and recomposing them, the Internet Protocol (IP) instead manages the journey of the packets, so that they are received by the right recipient.
In another article we also talked about the difference between TCP and UDP.

3) IP addresses
Computers on the network are identified by an IP address.
The IP address is like the nameplate of the machine, an identification number within the network.
Each PC has an internal IP, the one assigned by the router to distinguish one PC from another in the house and an external IP, the one assigned to the modem, with which all the PCs in the house are recognized on the internet.
Internet connection requests are made by the external IP, which can be variable or static depending on what is offered by the connection provider (i.e. by Fastweb or Telecom or other companies).
The internal IP, on the other hand, is useful for making home computers communicate with each other and transfer data.
These dynamics can be explored in the following articles:
- Who can see our IP address and what can they do with it?
- Why do computers at home have IP addresses of type 192.168.XX?
- How do we connect to the internet and why with the same Public IP?
- Find public IP and private IP and difference
- Find the IP of the router

4) DNS server
Speaking of the internet, it is important to know what DNS means.
A website is nothing more than a set of files, documents, images and much more, which are stored in a computer, called a web server, connected to the internet with a fixed IP address.
DNS servers are directories that associate the IP addresses of websites with names that are easy to remember, like in a telephone directory.
These servers, located all over the world, allow us to identify the IP of the computer (the server) where the or site is located without the need for us to remember it.
In this regard, we have seen several guides, including the one to change DNS on PC, Mac and on the router quickly.

5) The internet network
Putting together this type of information we should have in mind the general scheme of the huge internet network, where every website is hosted by a computer (which is the server) and has an IP address, just like every other computer in the world.
When my PC connects to the site, it makes a DNS request to the network provider (the one to which I pay the subscription), which associates an IP address with the name
Once the server hosting the site I requested is recognized, it allows you to download the data and present the web page with images, text and code on my computer.
In the same way, from my smartphone I can connect to the Whatsapp network, accessing the server that manages the service or other applications such as Facebook and Skype.

6) Connections in a home network (LAN)
Going back to talking about the home LAN network, we see that computers can be connected to the router / modem in two different ways, via Ethernet cable or wireless via wifi connection, without wires.
Several computers connected to each other through the router can talk to each other and exchange data and resources as we will see in point 10.
Smartphones, on the other hand, must necessarily connect to wifi, because they do not have an ethernet port.
On this, we have explained in another article which connection is better between ethernet and wifi and the difference between different ethernet cables.
Regarding wifi, however, we have seen the difference between 2,4 GHz and 5 GHz Wi-Fi networks and the difference between 802.11ac or 802.11n routers.

NOTE: The connection to the network can also be made through the electrical network, through devices called Powerline.

7) Wifi router configurations and network security
WiFi networks are absolutely more comfortable than cable networks, especially due to their smaller footprint and the ability to connect different devices such as smartphones, TVs; the alarm.
The only problem with Wifi is that it requires configuration and, above all, security to prevent anyone passing by from connecting and entering our computer network.
In this blog we have written how to configure a wifi router safely and what are the most important options to change on the router.
From the point of view of network security it is also worth knowing the firewall function integrated in most routers and the possibility of installing a firewall on the PC to prevent unauthorized connections from the outside.

8) Amplify wifi network
As explained in another guide, there are several ways to amplify the wifi signal of a wireless network, using repeaters, using two or more routers or even through the powerplugs I mentioned in point 6.

9) The ports and port forwarding configurations
In the case of using particular connections, for example to play online or to use Peer-to-peer programs or even to allow remote connections to our computer, it may be necessary to configure port forwarding.
Ports are the network addresses of programs and are represented by a number.
Just to understand, if from the outside I can connect to a computer using the IP address, but this is not enough, because we have to connect to a program.
This can be the remote desktop program or the program that manages the file transfer or even the program that runs a webserver and then manages the publication of a website.
The ports, for security reasons, are closed by routers and require to be opened manually if you use special programs.
On this, we have seen the guide on how to forward / open ports on the Router.

10 ) Remote desktop and file transfer
Two of the best advantages of LAN networks, corporate or home, are the remote desktop connection from one PC to another and the free transfer of files or the sharing of folders and printers.
Regarding the remote desktop, we have seen in another article the best solutions for remote PC control
As for the file transfer, however, we have the guides to share files and folders on the network and how to configure a network printer.

11 ) Network troubleshooting
If something is not working correctly, in other guides we have several ideas to solve each problem:
- Solutions for wifi and router connection problems
- If the pc does not connect to the internet, reset the network and web browsing
- How to fix internet connection problems
- Solutions to problems on internet connection and wireless networks

Great guide on computer LANs, internet and wifi

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