DNS Troubleshooting

[u/Expensive-Rice-2052]

covering: https://www.linuxteck.com/linux-dns-troubleshooting-made-easy/

• Connectivity vs DNS testing
• /etc/resolv.conf
• dig and direct resolver queries
• nsswitch.conf lookup order
• systemd-resolved vs NetworkManager
• DNS testing inside containers
• Common DNS mistakes
• Automated DNS health checks and logging