FRE-120 Fundamentals ⏱ 1 weeks

DNS: How the Internet Finds Things

A free, self-paced deep dive into DNS from first principles to advanced operations: how names resolve, every record type, caching and TTLs, dig troubleshooting, email DNS (SPF/DKIM/DMARC), DNSSEC, anycast, and DNS in the cloud and Kubernetes.

Syllabus

Module 1 — DNS fundamentals

  • What DNS is and why it exists
  • Names vs IP addresses
  • The players and the resolution journey

Module 2 — Hierarchy & resolution

  • Root, TLDs and authoritative servers
  • Delegation and registrars
  • Recursive vs iterative; the full walkthrough
  • Caching, TTL and the propagation myth

Module 3 — Records & zones

  • A, AAAA, CNAME, MX, TXT, NS, SOA, PTR, SRV, CAA, ALIAS
  • Zone files, glue and zone transfers
  • Email DNS: SPF, DKIM, DMARC

Module 4 — Tools & troubleshooting

  • dig, nslookup, host
  • Reading dig output; +trace
  • The troubleshooting ladder and common fixes

Module 5 — Advanced DNS

  • Cache poisoning and DNSSEC
  • DoH/DoT privacy; DDoS amplification
  • Anycast, GeoDNS, failover, split-horizon
  • Managed DNS and Kubernetes CoreDNS