Glossary

A record

A DNS record that maps a name to an IPv4 address.

AAAA record

A DNS record that maps a name to an IPv6 address.

ACME

A protocol for automating certificate issuance, validation, and renewal.

Authoritative nameserver

A DNS server that publishes official data for a zone.

CAA

A DNS record that restricts certificate authority issuance for a name.

CNAME

A DNS record that aliases one hostname to another canonical hostname.

Delegation

The parent-zone records that identify the authoritative nameservers for a child zone.

DKIM

An email authentication method that uses a domain-published public key to validate message signatures.

DMARC

An email policy and reporting mechanism based on SPF or DKIM authentication alignment with the visible From domain.

DNS

The distributed naming system that connects domain names to typed resource records.

Domain

A name in the DNS hierarchy. In this book, it often means a registered name that has been delegated to external authoritative nameservers.

Glue record

An address record supplied by a parent zone when it is needed to reach an in-zone nameserver.

HTTP

The application protocol used to request and deliver web resources.

HTTPS

HTTP carried over TLS, providing transport encryption and server authentication.

MX record

A DNS record that identifies mail exchangers for a domain.

Namespace

A managed naming area or suffix under which names may be registered.

NS record

A DNS record that identifies an authoritative nameserver.

Proxy

A system that receives traffic and forwards it to another service. It changes the network path and can affect logging, certificates, security, and policy.

RDAP

A structured protocol for accessing registration data.

Recursive resolver

A DNS server that follows referrals and caches answers for clients.

Registrant

The person or organization that registers and is responsible for a domain.

Registrar or registration service

The system through which a registrant creates and manages a domain registration.

SOA record

The DNS record containing core authority and timing information for a zone.

SPF

An email authorization policy describing which systems may send using a domain in the SMTP envelope.

SRV record

A DNS record that identifies the hostname and port for a named service.

Subdomain

A name below another domain, such as www.example.dpdns.org.

TLS

The protocol that protects HTTPS and other network connections with encryption and authentication.

TTL

Time to Live, the maximum caching lifetime advertised with a DNS record.

TXT record

A DNS record containing text, commonly used for verification and email policy.

Virtual host

A web server configuration that selects a site based on the requested hostname.

WHOIS

A legacy registration data lookup protocol and a general term still used for domain registration information.

Zone

The portion of the DNS namespace published as one administrative unit by authoritative nameservers.

Continue to Standards and Further Reading.