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DAY 07 of 12

Name, address, trust

Give the site a name, a real address, and a lock — and make it survive reboots

You can do… by end of day
  • Explain how a domain becomes an IP (the full resolution path) and create A/AAAA/CNAME/MX/TXT/NS records.
  • Point a real domain at your box and verify resolution with dig.
  • Explain TLS, PKI and the certificate chain that produces the lock icon.
  • Write a systemd unit so a service auto-starts and restarts, and read its logs with journalctl.
Deliverable

A named, HTTPS-trusted service that auto-restarts — verified with dig and journalctl.

Big-picture hook

Name, address, trust — the three things that make the internet feel real. Now: lock the doors and make it safe (and able to take money).

Concepts what you'll understand
  • DNS: why names exist; the resolution path (browser → resolver → root → TLD → authoritative); TTL and propagation.
  • The record types you'll actually use: A (name→IP), CNAME (name→name), MX (mail), TXT (verification/SPF), NS.
  • TLS & PKI: the encrypted channel proven by a certificate signed by a CA the browser trusts → the lock. Let's Encrypt + auto-renewal.
  • systemd, the heart of “it stays running”: units, systemctl start/stop/enable/status, Restart=always, and journalctl -u <svc> for logs.
The lab hands-on, ends with something live
  1. Name it: add an A record for your domain → your box; watch it propagate with dig +short.
  2. Inspect the lock: look at a TLS handshake / certificate and find the CA that signs it.
  3. Make it a service: write a systemd unit for your app; confirm it survives a reboot and restarts on crash.
  4. Diagnose: break the service on purpose, then find why it failed using journalctl.
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