The Domain Name System translates human-readable domain names to IP addresses. DNS resolution starts when you enter a URL in your browser. The browser checks its cache first for previous lookups. The operating system checks its resolver cache. The recursive resolver queries root name servers for TLD servers. TLD servers like .com direct to authoritative nameservers. Authoritative nameservers provide the actual IP address. DNS record types include A (IPv4), AAAA (IPv6), CNAME (aliases), MX (mail), TXT (verification). TTL values determine how long resolvers cache records. DNS propagation takes time as cached records expire globally. DNSSEC adds cryptographic signatures for security. DNS-based load balancing distributes traffic across multiple IPs. GeoDNS routes users to nearest server locations. Anycast routing directs traffic to the nearest DNS server. Common DNS providers include Cloudflare, AWS Route 53, Google Cloud DNS. DNS performance impacts website loading speed directly. Reduce time by minimizing unique hostnames. Use CDNs that optimize DNS resolution. Understanding DNS is essential for web performance and reliability.