The Domain Name System (DNS) is a critical component of internet functionality, translating human-readable domain names into numeric IP addresses that computers use to identify each other, like a digital phone book. Operating as a hierarchical and globally distributed database, DNS ensures scalability and fault tolerance, with different types of servers handling specific roles: recursive resolvers, root nameservers, top-level domain nameservers (TLD), and authoritative nameservers. Recursive DNS resolvers act as intermediaries, methodically querying other DNS servers to find the authoritative source, while authoritative DNS servers provide the definitive IP address for domains they manage. Common DNS issues such as server outages or outdated cache entries can disrupt connectivity, but can often be resolved by clearing caches or using alternative servers. Security is paramount, as DNS attacks can redirect users to malicious sites; thus, employing DNS Security Extensions (DNSSEC) and monitoring tools like New Relic's can enhance security and performance. Jon Garside of New Relic explains the importance of DNS in network navigation and security, offering insights into best practices and troubleshooting, while emphasizing the strategic role of DNS monitoring in protecting digital assets.