Domain Name System

The Domain Name System (DNS) is a distributed naming system that maps domain names to records, including IP addresses. Its hierarchical delegation lets many independently operated servers maintain a shared namespace.

DNS resolution: The process of finding DNS records by querying name servers, often through a recursive resolver. It traces how a domain name becomes an answer such as an IP address.
Domain name: A human-readable name in the DNS namespace, formed from labels separated by dots. DNS maps these names to records rather than treating them as network addresses.
A record: A DNS record that maps a domain name to an IPv4 address. It is the standard DNS answer for locating an IPv4-hosted service.
Hosts file: A local text file that maps host names to IP addresses on an individual computer. Unlike DNS, it provides manually maintained mappings without distributed delegation.
Recursive DNS resolver: A DNS server that obtains answers on behalf of clients, querying other servers and caching results. It performs the multi-step lookup that hides DNS delegation from most applications.
DNS zone: An administratively managed portion of the DNS namespace represented by a set of records. Zones divide the namespace into units that can be managed independently.
AAAA record: A DNS record that maps a domain name to an IPv6 address. It provides the IPv6 counterpart to the common IPv4 address record.
Multicast DNS: A protocol that resolves names on a local network using multicast rather than conventional DNS servers. It handles local discovery without relying on the global DNS hierarchy.
Root name server: A DNS server that directs queries toward the authoritative servers for top-level domains. It begins the referral chain for names outside a resolver’s cache.
DNS delegation: The process by which authority for a DNS subdomain is assigned to other name servers. Delegation links the hierarchy while allowing separate operators to control subdomains.

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