DNS, which stands for Domain Name System, is a crucial component of the internet infrastructure that facilitates human-friendly web addresses (domain names) to be translated into machine-readable IP addresses. It acts as a distributed database that helps computers and network devices locate and connect with each other over the Internet.
Here’s how DNS works
- Domain Names: Every device connected to the Internet, such as web servers, computers, or other networked devices, has an IP address, which is a numeric identifier. However, remembering IP addresses for every website or service is impractical for humans. That’s where domain names come in. Domain names are human-readable addresses associated with specific IP addresses.
- Domain Name Hierarchy: The domain name system is organized in a hierarchical structure. The hierarchy consists of different levels, separated by dots. The highest level is the root domain, followed by top-level domains (TLDs), second-level domains, and so on. For example, in the domain “www.example.com,” “.com” is the TLD, “example” is the second-level domain, and “www” is a subdomain.
- DNS Resolvers: When you type a domain name into your web browser (e.g., www.example.com), your computer needs to obtain the corresponding IP address. It starts by contacting a DNS resolver, typically provided by your Internet Service Provider (ISP) or configured manually. The DNS resolver is responsible for finding the IP address associated with the requested domain.
- DNS Query: If the DNS resolver doesn’t have the IP address in its cache (a temporary storage of previously resolved domain names), it initiates a DNS query. The query is sent to the root DNS servers, which provide information about the TLD servers.
- TLD Servers: The TLD servers direct the query to the authoritative name servers responsible for the specific TLD. For example, if the TLD is “.com,” the query is directed to the authoritative name servers for the “.com” TLD.
- Authoritative Name Servers: The authoritative name servers are responsible for storing and providing information about domain names within a specific domain. They return the IP address associated with the requested domain name.
- Caching: Once the DNS resolver receives the IP address, it stores the information in its cache for a certain period (Time-to-Live or TTL). This caching mechanism helps improve the efficiency of future DNS queries by avoiding the need to repeatedly query authoritative name servers for frequently accessed domain names.
- Response to Client: The DNS resolver returns the IP address to the client device (e.g., your computer), which can then use this information to connect to the desired server.
In summary, DNS serves as a critical translation service, converting human-readable domain names into machine-readable IP addresses. This systematic and hierarchical process enables efficient and scalable navigation on the internet by simplifying the way we access websites and services.