The DNS part came out fine, I knew to point all three domains at the same IP with A records.
Start by clarifying requirements and constraints, then propose a reverse proxy (e.g., Nginx) to route traffic based on the Host header or SNI. Walk through DNS configuration, TLS certificate management (e.g., Let's Encrypt with SNI), and operational concerns like security, monitoring, and scalability.
Pro tip: Mention that using a reverse proxy with SNI allows multiple TLS certificates on a single IP, and highlight automation of certificate renewal to avoid downtime. Also, discuss security hardening like isolating each site's processes and using a Web Application Firewall (WAF).
Ask about expected traffic, budget, and whether the businesses need isolation. Confirm that all domains can point to the same IP and that the server can handle the load.
Propose a reverse proxy (e.g., Nginx) to listen on ports 80 and 443 and route requests to separate backend services or directories based on the Host header or SNI. Consider using containers or virtual hosts for isolation.
For each domain, create an A record pointing to the server's public IP. Optionally, use CNAME records for subdomains. Ensure DNS propagation and TTL settings are appropriate.
Obtain individual TLS certificates for each domain using Let's Encrypt (e.g., via Certbot). Configure the reverse proxy to use SNI to present the correct certificate per domain. Automate renewal with cron jobs or systemd timers.
Implement monitoring, logging, and backups. Harden security with firewalls, regular updates, and isolation between sites (e.g., separate user accounts or containers). Discuss scalability options like load balancing if needed.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.