Title: TCP/IP protocol
Course: Informàtica 4t ESO v2 ang > Section: Topic 6. Networks and Device Connections

TCP/IP protocol

The letters TCP/IP stand for Transmission Control Protocol / Internet Protocol, the two protocols that enable information exchanges between networks and computers connected over the internet, with a very high reliability rate.

The TCP protocol establishes the bases for communication between two nodes that will exchange broken-up and packaged information so that when it reaches its destination it can be recomposed properly, without errors or duplication. The information does not travel whole in a single transmission but is segmented and packed into data to be recomposed at the destination.

The IP protocol establishes the transmission conditions for information packets that can reach the destination via different routes depending on the route status at any given time. It uniquely identifies all the computers in the network via an IP address comprising four blocks of numbers that look something like this: 193.47.145.40. The maximum value each field can reach is 255. This protocol fell short over time and subsequent versions emerged called IPv4 and IPv6.

 A network or network segment cannot have two computers with the same IP address because each one must be uniquely identified on the network. Assigning an address to a device can be a fixed value or may be variable depending on the system configuration.

Find the IP address of a computer

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

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Open the main menu in Windows. | Type cmd into the search box and click ‘Enter’ | A window from the old MS-DOS operating system will open

Then type in the command ipconfig and the system will give you the IP address of your computer.

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Enter the command ipconfig | Returned information. You can see the IP address assigned to the computer on the third line: 192.168.1.129. The fourth line shows the IP address of the local router establishing communication: 192.168.1.1

Activity: Find the IP Address of the Computer You Are Working On.

The DNS server

All computers connected to the internet are identified with their own IP address. With the emergence of the World Wide Web (WWW), new services were created to make the internet more user-friendly. One of them was the Domain Name Server (DNS) whereby it’s not necessary to know the IP address of the computer hosting the information you are requesting in order to access web server content. An easy to remember, textual name is used instead. Thus, for example, it's easier to remember the name www.gencat.cat than its IP address: 83.247.129.60.

Click on the following interactive activity for a better understanding of the process:

Source: RAD University

The purpose of DNS

Can we find out the IP address of a server? Yes, it’s possible but it’s not always immediate. Let’s take a look at the process. Open the MS-DOS window you saw in the example above and use the ‘ping’ command applied to the Government of Catalonia website.

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Type in the command: ping www.gencat.cat | Information returned. The sought IP address is 83.247.129.60

The actual address the network service has is 83.247.129.60, and it is equivalent to the domain entry www.gencat.cat . Therefore, if you enter the IP address in a browser, the result will be the same as entering the literal domain or URL (Uniform Resource Locator) value.

Activity: a) determine and check the IP address of www.edu365.cat . b) Find the URL of the address 173.194.45.24.