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📘 How DNS Works

A browser can ask for example.

6
lessons
~30 min
to learn
Adults
level
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What you’ll learn

  1. Names and numbersExplain why DNS connects human-readable names to network resource records.DNS is a hierarchical directory that lets applications use names while networks use addresses and other records.
  2. The resolver journeyTrace a lookup through a stub, recursive resolver, root, TLD, and authoritative server.A resolver follows delegations from the root toward the zone responsible for the requested name, often using cache along the way.
  3. Records and answersRecognize common DNS record types and the services they describe.A and AAAA publish addresses, CNAME creates aliases, and MX records direct mail; DNS records describe services as well as locations.
  4. Caching and changeUse TTL, negative caching, and replication to explain DNS speed and propagation.Caches reduce work but make changes age in over time, while replicated services improve reachability and resilience.
  5. Security and limitsDistinguish DNSSEC and encrypted DNS from HTTPS and other security layers.DNSSEC validates signed DNS data and encrypted transports protect query paths, but neither makes DNS a complete safety verdict.
  6. A complete lookupUse the layered lookup model to explain milliseconds, cold lookups, and troubleshooting.A cached answer can be nearly immediate; a cold lookup follows referrals, and a successful DNS answer is only the start of a web connection.

Questions this course answers

What is DNS mainly responsible for?

DNS answers naming questions; connection, routing, encryption, and content delivery are separate layers.

Put these DNS hierarchy labels from broadest to most specific.

The root delegates to a TLD, the TLD delegates to a domain, and the domain can contain a host label.

Match each DNS role to its job.

The roles divide client lookup, recursive work, hierarchy navigation, and source data.

What does a TLD nameserver usually provide?

The TLD layer narrows the delegation; it usually does not hold every host record.

Which record type carries an IPv6 address?

AAAA records publish IPv6 addresses; A records publish IPv4 addresses.

A CNAME record makes one name an ___ for another name.

CNAME identifies an alias and points resolution toward a canonical name.

Grounded in trusted sources

  • P. Mockapetris, RFC 1034, Domain Names - Concepts and Facilities, RFC Editor: https://www.rfc-editor.org/info/rfc1034/
  • P. Mockapetris, RFC 1035, Domain Names - Implementation and Specification, RFC Editor: https://www.rfc-editor.org/info/rfc1035/
  • IANA, Root Zone Management: https://www.iana.org/domains/root
  • IANA, Root Name Servers: https://www.iana.org/domains/root/servers
  • Cloudflare Learning Center, What is DNS?: https://www.cloudflare.com/learning/dns/what-is-dns/
  • Cloudflare Learning Center, DNS server types: https://www.cloudflare.com/learning/dns/dns-server-types/

Every Wunder lesson is built from real, reputable sources — never invented.

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