DNS Resolution

One question, asked of the root, a TLD and an authoritative server in turn — and then, for as long as the TTL allows, not asked at all.

Cold: 3 upstream queries

Warm: 0

Cache bounded by TTL

Scenario

Animation Speed: 1200ms

Resolver cachet = 0 s

Resolver cache is empty — only the root hints are known.

A laptop, its configured recursive resolver, and the servers that hold the DNS namespace: one root, a server for each top-level domain, and an authoritative server for each zone. The resolver starts with an empty cache — all it knows is the root servers' addresses, the "root hints" compiled into it.

Lookups So Far

www.example.com—

mail.example.com—

www.example.com—

www.example.org—

Round trips here: 4 ms to the resolver, 18 ms to a root, about 27 ms to a TLD and about 32 ms to an authoritative server.

Knowledge Check

Question 1 of 3

Who walks the hierarchy from the root to the authoritative server during a normal lookup?

DSAverse

DNS Resolution

Lookups So Far

Knowledge Check

See also

DNS Resolution

Lookups So Far

Knowledge Check

See also