Section 1 of 5
Follow it down
Root to answer, one referral at a time.
A name is resolved by asking a short series of servers, each of which knows only one useful thing: who to ask next. Five pieces following one query from a cold cache to an answer.
5 pieces in this section
- 01The question leaves, and does almost nothing on the way outA query carries no route and no plan; everything that happens next is decided by the servers it meets.
- 02Asked, and it declines to answerA root server does not know the answer and is not supposed to; it knows who to ask next.
- 03Another referral, one label further downEach step resolves exactly one label, and the delegation chain is the only thing holding it together.
- 04The one machine that actually holds the recordAuthoritative means something narrow and specific, and confusing it with recursive is behind a surprising share of outages.
- 05What a resolver is really doingThe recursive side keeps state, retries, and decides what to believe.