The DNS (Domain Name System) maps IP addresses to domain names.

When you plug a domain name in your browser URI box…

1. Local cache is checked first for a valid mapping to an IP. TTL (measured in seconds) defines the length of time a mapping in cache is considered valid. If not found…
2. Your router sends the request to a recursive DNS server (usually your ISP or OpenDNS, etc.). If not found…
3. The recursive server passes the request to a root name server. Root name servers (13 unique IP addresses for them) keep track of the DNS servers in the next level down: top-level domain servers.
4. Top-Level Domain (TLD) Servers are split up by extensions (.com, .org, .co.uk, etc.). TLD servers keep track of DNS servers one level down: authoritative name servers.
5. Authoritative name servers are used to store DNS records for domains directly (the buck stops here). The IP mapped to the domain name you requested is sent back to you and your browser uses it to access the website you want to go to.

This whole process is automagic with browsers but dig can do all this manually (and show us the results).

Syntax:

dig [domain] @[dns-server-ip]

# Example:
dig google.com @1.1.1.1