Title: TCP/IP Protocol
Course: Appdate yourself 4t ESO (in English) - Curs 2017/18 > Section: Topic 8 Networks

TCP/IP Protocol

The acronym TCP / IP comes from Transmission Control Protocol / Internet Protocol, the two protocols that allow, with a very high reliability rate,  the exchange of information between networks and computers connected to Internet.

TCP provides the basis for communication between two nodes which exchange broken up and packaged information  in order to reach the destination and be reconstruct the information correctly, without errors or duplication.

The IP protocol establishes the conditions for the transmission of information packets that can take different paths depending on the state of the routes at all times. It serves to uniquely identify all computers on the network through an IP address consisting of four numeric blocks similar to the following: 193.47.145.40. The maximum value that each field can reach is 254. This protocol did not have the strength to support all of the increasing numbers of IP addresses and therefore, new versions called IPv4 and IPv6 were created.

A network or network segment can not have two computers with the same IP address and each computer must be clearly identified on the network. Assigning the address of a device can be a fixed value or may be variable according to the system's configuration.

Find out the IP address of a computer

There are various ways to find out the IP address of any given computer.  If you are using Windows, use the following steps:

* |  |
Open the main page of Windows. | In the search box, write the following: cmd and click 'enter'. | A window of the old operating system MS-DOS will open.

With the command ipconfig, the system will give us the IP address of the computer in question.

* | *
Entrance of the ipconfig command. | Information returned. On the third line, you can see the computer's IP address: 192.168.1.129. The fourth line shows the router's address with which communication has been established: 192.168.1.1

Activity: Find out the IP address from the computer on which you are working.

DNS Server

All computers connected to internet have their own IP address. With the coming of the World Wide Web (WWW), new services were created in order to make internet more user-friendly. One of these services is called the Domain Name Server (DNS) in which a web server does not need to know the IP address that hosts the computer we are requesting in order to access the content of a web server.  Instead, an easy to remember, textual name is given.

For example, it is easier to remember the name www.gencat.cat than your IP: 83.247.129.60.

Take a look at the following interactive activity in order to better understand the process:

Source: RAD University

Function of DNS

Can we find out the IP address of a server?  Yes, it is possible but it's not instant!  Let's take a look at the process.

Open the window MS-DOS that you saw in the above example and add the word 'ping' + the IP address or whichever address you wish, such as, www.google.com. If the server is working, you will see the IP address of the server and be able to verify that it is responding correctly

* | *
How to write the command: ping + www.google.com | Information returned. The nearest IP address for google found is  173.194.34.211

The nearest functioning IP address for google is  173.194.34.211 which is equivalent to the address www.google.com, therefore, if you write the IP address in your browser, the result will be the same as the text domain name or URL (Uniform Resource Locator).

Activity: a) Find out the IP address of www.twitter.com  b) Find out the URL of 31.13.83.16.