DNS: turning names into addresses

What happens between typing a hostname and the first packet leaving your machine.

The lookup

Computers route on addresses, people remember names. DNS is the translation layer between the two.

The chain

The browser checks its own cache
Then the operating system cache
Then the configured resolver, usually your router or a public one
The resolver walks the hierarchy: root servers, then the top-level domain, then the authoritative server for the domain

Why TTL matters

Every record carries a time-to-live. A low TTL makes changes propagate quickly but increases lookup traffic. Lower it a day before you plan to move a service, not on the day.