DNS Resolution Explained

DNS (Domain Name System) is the phonebook of the internet. It translates human-readable names (example.com) into IP addresses (93.184.216.34).

The Hierarchy

1. Stub Resolver: Your computer's local cache.
2. Recursive Resolver: Usually your ISP or Google (8.8.8.8). It does the legwork.
3. Root Servers (.): The 13 logical servers at the top of the chain. They know where .com, .org, etc., live.
4. TLD Servers (.com): They know where example.com lives.
5. Authoritative Nameservers: The actual server that holds the IP for example.com.

The Query Flow

1. You: "Where is example.com?"
2. Recursive: "I don't know. Hey Root, where is .com?"
3. Root: "Go ask the .com TLD server at this IP."
4. Recursive: "Hey .com TLD, where is example.com?"
5. TLD: "Go ask the Authoritative Server at this IP."
6. Recursive: "Hey Authoritative Server, what is the IP for example.com?"
7. Authoritative: "It's 93.184.216.34."
8. Recursive: "Here you go, user."

Security Implications

DNS was designed without security.

• DNS Spoofing: An attacker replies faster than the real server.
• DNS Tunneling: Exfiltrating data via DNS queries (since DNS is rarely blocked).

DNSSEC adds cryptographic signatures to records to prevent spoofing, but adoption is complicated.