DNS terminology

The language behind the answers.

A short guide to the terms you will see in the explorer.

Recursive resolver

A service that finds DNS answers on a client’s behalf and may return cached results. Cloudflare, Google, and Quad9 are the public resolver options here.

Authoritative nameserver

A server that answers for a DNS zone it hosts. Delegation identifies which nameservers are responsible for a zone.

TTL · Time to live

The number of seconds a resolver may cache a record. A recursive response often shows the remaining cache lifetime.

A / AAAA

IPv4 and IPv6 address records.

CNAME

An alias pointing one DNS name at another.

MX

Mail exchange records name the servers that accept mail, with a preference value. Lower preference values are tried first.

TXT

Text records used for information such as SPF policies, domain verification, and other application data.

NS / SOA

Nameserver records identify DNS servers; the start of authority record describes zone administration and timing information.

PTR

A reverse DNS record mapping an address’s reverse lookup name to a hostname.

CAA

Specifies which certificate authorities may issue certificates for a name, subject to the applicable CAA processing rules.

SRV

Locates a service using a target hostname, port, priority, and weight.

DS / DNSKEY

DNSSEC records used in chains of trust and signature verification. Displaying them alone is not DNSSEC validation.

HTTPS / SVCB

Service binding records that advertise service endpoints and connection parameters.

NOERROR / NXDOMAIN / SERVFAIL

DNS response codes: a completed response (possibly empty), a nonexistent name, or a server failure.