DNS is a globally distributed, hierarchical database. When you query introsweb.com, a complex chain of UDP requests fires across the globe.

The Resolution Path

  1. Stub Resolver: The OS checks its local cache. If missing, it queries the Recursive Resolver (usually provided by the ISP or a public resolver like 1.1.1.1).
  2. Root Nameservers: The Recursive Resolver queries one of the 13 logical Root Servers (.). The Root Server responds with the IP of the TLD Nameserver for .com.
  3. TLD Nameservers: The Recursive queries the .com TLD server. The TLD server responds with the IP of the Authoritative Nameserver for introsweb.com.
  4. Authoritative Nameserver: The Recursive queries the Authoritative server, which returns the final A record (IPv4 address).

Caching and TTLs

Every node in this chain caches the result based on the Time To Live (TTL) set by the Authoritative server. A TTL of 300 means resolvers will cache the IP for 5 minutes before re-querying.

While low TTLs are great for failover, they increase the latency tail-risk for users whose local cache frequently expires.