The Domain Name System maps a hostname such as google.com to an IP address such as 142.250.80.46. Computers find each other with numbers. People type names. Without DNS you would memorize a long number for every site. A page load starts with that lookup. You never have to type 142.250.80.46 into the bar.
The lookup process works in steps. Your browser first checks its own cache to see if it already knows the IP address. If not, it asks the operating system, which checks its cache too. If the answer still is not found locally, the request goes to a recursive resolver, usually run by your internet provider. net).
That server points to the authoritative name server for the specific domain, which finally returns the IP address. This whole chain typically completes in under 100 milliseconds.
DNS records come in several types. An A record maps a domain to an IPv4 address. AAAA records do the same for IPv6. CNAME records create aliases, pointing one domain name to another. MX records tell email servers where to deliver mail for a domain. TXT records hold arbitrary text data and are commonly used for email authentication (SPF, DKIM) and domain verification.
NS records specify which name servers are authoritative for a domain.
Because every internet request starts with a DNS lookup, DNS performance and security matter for everything online. Cached answers are fast, often a few milliseconds. A cold lookup that walks from root to TLD to the authoritative server is slower, still usually under 100 milliseconds. Slow DNS still adds latency to every uncached page load.
DNS poisoning attacks redirect users to fake websites by injecting bad records into resolver caches. DNSSEC adds cryptographic signatures to DNS records to prevent tampering. 8) offer faster and more secure alternatives to default ISP resolvers. DNS is invisible to most users, but it is one of the most critical pieces of internet infrastructure. DNS was specified in RFC 1034 and 1035 (1987).
Names map to records. Resolvers walk from the root to the authoritative server.
DNS Resolution Journey
Follow a domain name as it gets translated into an IP address
DNS translates human-readable domain names into IP addresses. The lookup traverses a hierarchy of servers, from local caches to authoritative nameservers, with results cached at each level for faster future lookups.