Fundamentals of DNS
Explore the fundamentals of the Domain Name System to understand how domain names are translated into IP addresses through a hierarchical address resolution process. Learn about root servers, top-level domains, name servers, and the role of DNS caching in improving performance and reducing load. This lesson provides practical insights using the dig command to illustrate how DNS queries work and how caching impacts domain updates and propagation delays.
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What is DNS?
DNS stands for Domain Name System and is a hierarchical system to identify computers (or servers) by name. Essentially, it provides us with an IP address if we ask for a domain name. This process is called address resolution. By the way, the DNS is described in the RFC 1034 specification.
The hierarchical part of DNS refers to the structure. It's composed of root servers at the top (the root zone), then name servers for each TLD zone, and then further name servers for each domain (the domain zone), and so forth.
This is also reflected in the structure of domain names. Let’s take a look at www.educative.io for example:
Its correct DNS description would be:
www.educative.io.
The last dot is usually omitted, but computers use it internally. The last dot refers to the root zone. Going back from the last dot, we have the TLD (io in this case), the domain name (educative), and the subdomain (www). Each part of the domain name corresponds to a hierarchical level in the DNS. Subdomains can have multiple levels over subdomains under them.
TLD stands for top-level domain. The image ...