DNS Basics
What is DNS and how does the DNS resolution process work step by step?
What is DNS and how does the DNS resolution process work step by step?
DNS (Domain Name System) translates human-readable domain names to IP addresses. Resolution flow: browser cache → OS cache → resolver (ISP/configured DNS) → root servers → TLD servers → authoritative nameservers. Common record types: A (IPv4), AAAA (IPv6), CNAME (alias), MX (mail), TXT (verification).
DNS is fundamental to how the internet works. DevOps engineers need to understand DNS for configuring domains, troubleshooting connectivity issues, setting up load balancers, managing SSL certificates, and configuring email services.
DNS troubleshooting commands
Local DNS configuration
- Forgetting about DNS caching when making changes (TTL)
- Using CNAME at the apex/root domain (not allowed)
- Not understanding DNS propagation delays
- What's the difference between A records and CNAME records?
- What is TTL and why does it matter?
- How would you set up DNS for a load-balanced application?
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