Structure and address practices on the Internet

The backbone of the global telecommunication network, the Internet, comprises servers connected to each other through high-speed data communications connections. Numerous local area networks (LANs) are connected to these servers. The LANs, for their part, offer individual users the possibility to connect to the Internet through different devices (computers, TVs, smartphones, etc.).

Your device, when it accesses the Internet, is assigned a so-called Internet address which identifies it. Without this address your device cannot connect to the Internet, but at the same time, it means that your movements in the Internet can be traced – often with a fair amount of detail. So, keep in mind that your activities in the Internet leave traces.

This Youtube video clip will tell you everything you need to know about the structure of the Internet in just over five minutes.

Domain Name System – DNS

The networks and services in the Internet also have plain-language names, called domain names. The plain-language domain names, such as, are assigned to the Internet addresses by the Domain Name System (DNS). Understanding the principles of this system will help you remember where different web services are located, since the domain name often consists of these parts:“service name”. “service domain”. “area code”.


For example, the first part of, “https://” refers to the data transfer protocol. The second (www) and third (helsinki) parts indicate that the server is called “www” and it operates under the domain “helsinki”. The fourth part of the address (.fi) indicates that the domain is located under the fi top-level domain (Finland). The last part, meaning “en” and “news” separated by forward slashes, indicate that information is being sought from a directory called “news” in the English language version of the website.

The following table shows some more examples of Internet addresses.

Transfer Protocol Service address or domain name or DNS name Service
http:// Yle’s www server.
https:// Secure connection to the University of Helsinki Moodle learning environment (s = secure).
mailto: E-mail address.

The IP addresses system

DNS addresses – such as – are important to you because they are easy to understand, but in reality most communication on the Internet is based on IP (Internet Protocol) addresses, which are long series of numbers (such as IP addresses allow each computer connected to the Internet to be identified, enabling communication between different computers.

An example: if you want to look at the web pages of the Aalto University, your computer will find out the IP address associated with the server. After finding this information, your browser sends a request to Aalto’s IP address ( for the front page of the www server. At this point, the Aalto server is informed that the request was sent by your computer, so the server will send the front page to your computer’s IP address.

If you wish to know the current IP address of your own computer, visit the address If you are connected to the university network, the first numbers will be 128 and 214.