What is DNS and how does it work? What are the main nodes in this system?

DNS (Domain Name System) is a system of domain names that translates human-readable website names (e.g., example.com) into IP addresses understandable by computers (e.g., 93.184.216.34). This is necessary because establishing a network connection requires an IP, but it is easier for people to remember names.

How it works:

1. The user enters a domain name in the browser.
2. The request is sent to the local DNS server (usually the provider's).
3. If the local server does not know the IP, it contacts the root DNS servers.
4. The root server redirects to the top-level domain (TLD) server, e.g., .com.
5. The TLD server directs to the authoritative DNS server for the specific domain.
6. The authoritative server returns the IP address.
7. The local server caches the response and sends the IP to the client.

Main nodes of the DNS system:

• Root DNS servers — the top of the hierarchy.
• TLD DNS servers — responsible for zones like .com, .org, .ru, etc.
• Authoritative DNS servers — store records for specific domains.
• Recursive DNS servers — perform chain searches for the client.

Thus, DNS is a distributed and hierarchical system that provides fast and scalable resolution of names to IP addresses.