URL

What is a URL and what is its purpose?
A Uniform Resource Locator (URL) is the full address used to locate and access a specific resource on the Internet. It tells a browser how to access the resource and where it is located. A URL combines a protocol (such as http:// or https://), a domain name (like www.bbc.co.uk), and a path to the specific resource (such as /index.html). By combining these parts, a browser can find the correct server and request the exact file or webpage needed.

What are the parts of a URL?
A URL has several components, each serving a distinct role. The protocol specifies the method of communication between the browser and the server — common examples are http and https (which is the secure version using encryption). The subdomain usually appears as www but can be something else such as mail, blog, or shop to represent different sections of a site. The domain name itself includes the second-level domain (like bbc) and the top-level domain (TLD) such as .co.uk, .com, or .org. Finally, the path points to the specific file or directory within the site (for example /news/today.html). URLs may also include query strings (?id=123) or anchors (#section1) to access specific data or sections of a page.

4

What is the Domain Name System (DNS) and what does it do?
DNS is a hierarchical naming system that translates human-readable domain names into numerical IP addresses. When a user enters a domain name in their browser, the computer sends a DNS query to a DNS server. This server looks up the domain and returns the corresponding IP address, which the browser then uses to contact the correct web server. This process is called name resolution. DNS makes the Internet user-friendly, allowing people to type memorable names instead of long numbers.

4

How is the DNS structured and how does it resolve names?
The DNS is organised in a hierarchical structure of distributed servers. At the top are 13 root DNS servers, which store pointers to all top-level domain (TLD) servers such as .com, .org, .net, or .uk. These TLD servers store information about authoritative name servers for specific domains (for example, bbc.co.uk). When a DNS server receives a query it cannot answer, it will either recursively query other DNS servers on behalf of the client or refer the client to the next relevant server down the hierarchy. This continues until the specific authoritative server returns the IP address. If no record is found, the browser displays an error message such as “DNS address could not be found.”

4

What are Internet registries and why are they important?
Internet registries are official organisations that allocate and manage IP addresses and domain names globally to prevent duplication and conflicts. There are five main Regional Internet Registries (RIRs) around the world. These registries assign large blocks of IP addresses to Internet Service Providers (ISPs) and organisations, and they maintain central databases to ensure each address is unique. They also oversee the rules and policies for domain name allocation, ensuring the Internet remains stable and consistent worldwide.

How are domain names purchased and registered?
Domain names are obtained through domain registrars, which are companies accredited to register domains on behalf of the registries. Users can search for available names and purchase them in various TLDs (like .com, .net, .org, .uk). Once purchased, the registrar links the domain name with the owner’s IP information and enters it into the global DNS system. This ensures the name is unique and accessible anywhere on the Internet, preventing anyone else from registering the same domain.

4

Summary

A Uniform Resource Locator (URL) is the full address for a resource on the Internet, combining a protocol, domain name, and path. The Domain Name System (DNS) translates human-readable names into machine-readable IP addresses through a hierarchical structure of root, TLD, and authoritative servers. Internet registries allocate unique IP addresses and oversee the global domain name system, while registrars sell and register domains for public use. These systems work together to allow users to find and access websites easily and reliably without memorising numeric addresses.