The Domain Name System (DNS) is a hierarchical, distributed database that maps domain names to information computers need, most commonly IP addresses. When you visit example.com, a resolver queries the root servers, then the TLD’s servers, then the domain’s authoritative nameservers to find the answer.
DNS stores different kinds of data in resource records, including:
- A / AAAA: IPv4 / IPv6 addresses.
- CNAME: an alias to another name.
- MX: mail servers for the domain.
- TXT: free-form text used for verification and email security.
- NS: the authoritative nameservers.
Answers are cached according to each record’s TTL, which is why DNS changes can take minutes to hours to be seen everywhere (often called “propagation”).
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Related terms
- Nameserver
- A nameserver is a DNS server that holds and answers queries for a domain's records; you set which nameservers are authoritative at your registrar.
- A record
- An A record is a DNS record that maps a domain or subdomain to an IPv4 address, telling browsers which server hosts the site.
- CNAME record
- A CNAME record makes one hostname an alias of another, such as www.example.com pointing to example.com or to a hosting provider's hostname.
- MX record
- An MX record tells the internet which mail servers accept email for your domain, with priority numbers deciding the order they are tried.