What is DNS?
Why Interviewers Ask This
This is a classic screening question for Networking roles. Hiring managers ask it early in interviews to gauge your baseline understanding and determine if you can communicate technical concepts clearly.
Answer
DNS (Domain Name System) is the Internet's "phone book" — it translates human-readable domain names (like google.com) into machine-readable IP addresses (like 142.250.80.46). Without DNS, users would need to memorize IP addresses for every website. DNS is a distributed, hierarchical system. When you type a URL, your computer first checks its local cache, then queries a Recursive Resolver (typically your ISP's), which then queries Root Servers (13 clusters), then TLD servers (.com, .org), then Authoritative Name Servers for the specific domain. The result is cached for a duration set by the TTL (Time to Live). DNS records include: A (IPv4 address), AAAA (IPv6), CNAME (alias), MX (mail server), TXT (text, used for SPF, DKIM), NS (name server).
Common Mistake
Don't just define the term — demonstrate that you understand when to use it and when not to. Showing awareness of trade-offs is what separates average from strong Networking candidates.