How are domain names translated into IP addresses?

Domain names are translated into IP addresses through a process called Domain Name System (DNS) resolution. DNS is a distributed hierarchical system that serves as the "phonebook" of the internet, translating human-readable domain names into machine-readable IP addresses.

Here's how the DNS resolution process works:

1. DNS Query: When a user enters a domain name (e.g., example.com) into their web browser or other network-enabled application, the device initiates a DNS query to resolve the domain name into an IP address.

2. Local DNS Cache: The DNS resolver on the user's device first checks its local DNS cache to see if it has a recent record of the domain name's IP address. If the information is cached and still valid, the resolver can immediately return the IP address without further queries.

3. Recursive DNS Server: If the domain name's IP address is not cached locally or has expired, the DNS resolver sends a recursive query to a recursive DNS server (often provided by the user's internet service provider or a third-party DNS resolver).

4. Root DNS Servers: If the recursive DNS server does not have the requested domain name's IP address in its cache, it starts the resolution process by querying the root DNS servers. The root DNS servers provide information about the authoritative name servers for top-level domains (TLDs), such as .com, .org, .net, etc.

5. TLD Name Servers: Based on the TLD of the requested domain name (e.g., .com), the recursive DNS server queries the corresponding TLD name servers to obtain the IP addresses of the authoritative name servers responsible for the specific domain extension.

6. Authoritative Name Servers: The recursive DNS server sends a query to the authoritative name servers for the requested domain name. These name servers store the DNS records (including the IP address) for the domain and respond with the corresponding IP address.

7. DNS Response: Once the authoritative name servers provide the IP address for the requested domain name, the recursive DNS server caches the information and returns the IP address to the user's device. The device then uses the IP address to establish a connection to the desired web server and retrieve the requested content.

This entire process happens behind the scenes and typically takes only a fraction of a second, allowing users to access websites using human-readable domain names without needing to know the corresponding IP addresses.