A Query Is a Question Object
What is a DNS query made of, and when are two lookups actually the same lookup?
Open Session 01Sessions
DNS track sessions
The Resolver Walks Down the Tree
How does a resolver get from the root to an answer, and what does each hop actually decide?
Open Session 02Delegation Is a Referral, Not an Answer
When a server responds, how does the resolver decide whether it just got an answer, a hand-off, or a dead end?
Open Session 03The Cache Answers First
Why do most DNS queries never leave the resolver, and what exactly decides hit versus miss?
Open Session 04TTL Is a Clock, Not a Config
If a record says TTL 300, what number does a client actually receive two minutes later, and who removes the entry when it hits zero?
Open Session 05CNAME Restarts the Question
A CNAME is not an A record. How does asking for an A record still end at one, and what stops the chain from running forever?
Open Session 06Failure Has Flavors
NXDOMAIN, SERVFAIL, and a timeout all mean "no IP address". Why does a resolver treat one as an answer and the others as reasons to try again?
Open Session 07Build the Toy Resolver Loop
What does the smallest readable resolver look like when validation, cache, tree walk, and CNAME restart are connected in one loop?
Open Session 08