Internet domains: what are they and how do they work?

Looking for answers online is natural nowadays, but what mechanisms lie behind a web search? Domain names are the real key to exploration through browsers. So let’s find out what an Internet domain is, why it is important and what organisations define how it works.

What is an Internet domain?

Today, the Internet is the most accessible source of free information on the planet: a browser is enough to plunge us into a sea of knowledge. To get oriented, however, we need precise directions: navigating the web would be impossible without domain names.

In practical terms, however, what is an Internet domain? A text label to easily and uniquely identify an online resource. Any web page has one and it corresponds to the set of words divided by dots that you find in the search bar at the top, after “https” in the URL. Let’s take an example: Young Platform’s Academy is recognised by the string academy.youngplatform.com, its full domain name. 

Before analysing its components, however, we must ask ourselves why an Internet domain is necessary. In a nutshell, any device connected to the Internet has an IP address, but this code is too complex for its owner to memorise. The IP, in fact, consists of a series of at least four numbers (e.g. 123.4.56.789), which becomes an even longer alphanumeric string in the latest IPv6 version. In short, the IP address is not easy to remember, so it is associated with an understandable name, the Internet domain.

In this way, to retrieve a web page, there is no need to indicate the IP address of the server hosting its contents – you just enter the domain name of the site. After that, it is the Domain Name System (DNS) that tells the browser the precise location of the resource. In practice, the domain name system works like a telephone book, pairing names and numbers: let’s define how many types of domain there are, so as to explain in detail what the DNS is and how it works.

Domain name levels

Let’s take the example of academy.youngplatform.com. The name is divided by the dots into 3 parts: starting from the right, we have the Top Level Domain (TLD), i.e. “.com”, then the Second Level Domain (SLD) “.youngplatform” and the sub-domain “.academy”.

TLDs are also called ‘extensions’, because they clarify the type of domain, like files on a computer. For example, the generic Top Level Domain (gTLD) .info is used for pages of an informative nature, just as each country has its own Country Code Top Level Domain (ccTLD); the .uk identifies British sites, and the .fr French ones. TLDs, therefore, are chosen on the basis of certain criteria, since they communicate the general purpose and content of the web page; however, they are ‘pre-formatted’, and new ones cannot be created directly by users.

Second level domains (SLDs) and subsequent sub-domains, on the other hand, represent the ‘customisable‘ part of the name. Although they are subordinate to the TLDs, they are the component that really identifies a website. In youngplatform.com, for example, the user can recognise the exchange thanks to the second level, while the third (.academy or .pro) specifies the ‘section‘ of the Young Platform ecosystem. Other sites, such as Wikipedia, use the latter position to indicate the ‘linguistic’ sub-domain, distinguishing English content (en.) from other languages, thus moving the ccTLDs to the third level.

Domains can go beyond the third level, but do not have unlimited space: the maximum length is 253 ASCII characters and each ‘position’ cannot contain more than 63 bytes. In short, a maximum of 127 levels can be obtained, divided by 126 points (considered characters). Despite these limits, the combinations are almost infinite: the Domain Name System has to manage this immense structure of subordinates and make it scalable, let’s find out how it works.

DNS: what is it and how does it work?

The DNS is the server system used by the Internet to store and ‘resolve’ domain names, so as to translate them into IP addresses and indicate which device is the host of the relevant web page, i.e. where its contents are stored. This is possible thanks to its distributed database and its hierarchical structure: the DNS is a ‘tree’ of servers, divided into roots and ‘zones’. In particular, each server is dedicated to a precise level and domain name, so as to distribute the operational and memory load. Having defined the structure, we can therefore delve into how the DNS works.

There are four types of DNS servers, which make up the domain name system:

The objective of DNS, through its components, is to retrieve the IP address corresponding to the domain that the user (client) enters in the browser. Let us look at the steps in the process in points: 

The Domain Name System, in practice, is a set of ‘switchboards‘ that work together to transfer a ‘call‘ to a specific recipient, i.e. the browser‘s request to a server to load a certain site. The functioning of the DNS concretely demonstrates what an Internet domain is and how it works, but who distributes the names and how?

Where to buy an Internet domain? ICANN and Registrars

There is a body in charge of monitoring the domain name system: it is the Internet Corporation for Assigned Names and Numbers, or ICANN. This non-profit organisation administers the allocation of IP addresses and names, just as it manages the DNS, using its own sub-units (such as IANA for ccTLDs) or accredited third-party entities. In a nutshell, ICANN has issued thousands of TLDs over time, delegating the care of the databases to Registries and assigning the sale of subdomains to Registrars.

For instance, .fly domain names can be registered with Google Domains, but are only granted to airlines, travel agencies and verified travel retailers. Other Top Level Domains, on the other hand, are not ‘sponsored’, but available to all for purchase. Clearly, there cannot be two copies of one name, so sellers (Registrars) and resellers must notify the Registries whenever a domain is registered under a given extension.

By cross-referencing the data of all the Registries, it is then possible to create the WHOIS Directory: a complete list of all domain names and IP addresses, associated with certain owner information (such as e-mail and telephone number). In this way, anyone can find out whether a certain domain is still free and, if so, who to contact to discuss the purchase.

Registering an Internet domain means that no one else will be able to use it to represent their online services for the duration of the contract (lasting up to 10 years). This advantage is sometimes highly paid for, in fact among the most expensive  we find figures even in the millions. Price speculation, therefore, has characterised the history of Internet domains  to date, even after the dotcom bubble burst, which, however, rather concerned the companies built around these sites.

So we have explained what a domain is and how it works on the internet, but is it possible to register one on blockchain? It is one of the latest applications of cryptocurrency technology: NFT domains.