Understanding DNS and Its Role in the Internet

DNS (Domain Name System) is a fundamental component of the internet's infrastructure, responsible for translating human-friendly domain names (like www.google.com) into IP addresses that computers use to identify each other on the network. This process is essential for accessing websites and services online. Below is a concise overview of key DNS concepts and how DNS queries are resolved, leading into an introduction to AWS Route 53.

Key DNS Concepts

• Domain Name System (DNS): Translates domain names to IP addresses.
• Hierarchical Structure: Domains have a hierarchical structure, e.g., from .com to example.com to www.example.com.
• Domain Registrar: A service where domain names are registered, e.g., Amazon Route 53, GoDaddy.
• DNS Records: Entries in a DNS database, including types like A, AAAA, CNAME, and NS.
• Zone File: Contains all DNS records for a domain, mapping hostnames to IP addresses.
• Name Servers: Servers that resolve DNS queries.
• Top-Level Domain (TLD): The last part of a domain name, e.g., .com, .org.
• Second-Level Domain: The part of a domain name directly below a TLD, e.g., example in example.com.
• Fully Qualified Domain Name (FQDN): The complete domain name for a specific host, including the TLD and any subdomains.

DNS Resolution Process

1. Starting the Query: A user's web browser requests a domain, e.g., example.com.
2. Local DNS Server: The query first goes to a local DNS server, typically provided by the ISP or the user's network.
3. Root DNS Server: If the local DNS doesn't know the address, it queries a root DNS server, which knows where to direct queries for TLDs.
4. TLD DNS Server: The root server points to the TLD server (e.g., for .com), which knows the DNS servers for second-level domains.
5. Domain's DNS Server: The query is then sent to the DNS server responsible for the specific domain, which knows the IP address associated with the domain name.
6. Final Resolution: The domain's DNS server responds with the IP address of the server hosting the website, allowing the user's browser to access it.