DNS
DNS
A distributed system that maps domain names to records about network and service resources.
Glossary
Definitions provide orientation; linked guides explain details and limitations.
Domains
WHOIS
A protocol and set of public registration data whose format and availability depend on the registry and zone policy.
DNS
A record
A DNS record that maps a domain name to an IPv4 address.
DNS
AAAA record
A DNS record that maps a domain name to an IPv6 address.
DNS
MX
A DNS record that specifies the mail servers and their priority order for a domain.
DNS
NS
A delegation DNS record that points to the authoritative servers of a DNS zone.
DNS
TTL
The duration in seconds a DNS answer may be cached by a resolver before being discarded.
Networks
PTR
A reverse DNS record that maps an IP address to a domain name.
DNS
DNSSEC
DNS extensions that cryptographically verify the authenticity and integrity of DNS answers.
Networks
CIDR
An IP prefix notation where the number after the slash indicates the length of the shared network portion in bits.
Networks
ASN
An Autonomous System number that participates in route exchange between networks on the internet.
Networks
FCrDNS
A check where the PTR name is resolved forward and the result includes the original IP address.
SSL and security
TLS/SSL certificate
A signed document that binds a public key to domain names and is used when establishing a secure TLS connection.