DNS and name resolution

Cheat sheet

• getent hosts example.com how the system actually resolves it (for apps)
• resolvectl status DNS servers and search domains
• dig +short example.com a quick answer (IP only)
• dig example.com MX a specific record type
• dig @8.8.8.8 example.com check via a public DNS server
• dig +trace example.com where delegation breaks
• resolvectl flush-caches clear the cache
• local overrides go in /etc/hosts; permanent ones in netplan's nameservers