Glossary

Short codes and terms used throughout DNS Lister.

Protocols

DNS

Domain Name System

CIDR

CIDR (Classless Inter-Domain Routing) - replaced fixed Class A/B/C address blocks; written as an IP plus a slash and prefix length (e.g. 203.0.113.0/24), where the prefix sets how many bits are fixed and the rest form the address range.

RDAP

Registration Data Access Protocol. The new version of 'WHOIS' for the modern age.

RDAP BOOTSTRAP

ICANN's registry of which RDAP server handles each TLD (data.iana.org/rdap/dns.json)

REGISTRY

The organization that operates a TLD (e.g. Verisign for .com) and its RDAP/WHOIS server

REGISTRAR

The company a domain owner actually bought the domain through (e.g. GoDaddy) — distinct from the registry

ICANN

Internet Corporation for Assigned Names and Numbers — oversees the domain name system

EPP

Extensible Provisioning Protocol - the protocol a registrar uses to talk to a registry to register, renew, transfer, and update a domain; also where EPP status codes like clientTransferProhibited come from.

IANA

Internet Assigned Numbers Authority — the ICANN function that publishes the root registries this app reads: which RDAP server handles each TLD (data.iana.org/rdap/dns.json), and which WHOIS server to ask (whois.iana.org)

NIC

Network Information Center - historically the organization that ran a network/domain registry (e.g. InterNIC); still used today as a synonym for "registry operator" (e.g. ".xyz NIC") and in registrar contact terms like "NIC handle".

REGISTRANT

The person or organization that actually owns a domain registration - distinct from both the registrar (who they bought it through) and the registry (who operates the TLD).

THICK REGISTRY

A registry that stores the registrant's full contact details itself (e.g. .org, most new gTLDs) - a WHOIS/RDAP lookup gets a complete answer straight from the registry.

THIN REGISTRY

A registry that stores only the sponsoring registrar's name - a WHOIS/RDAP lookup has to be re-directed to that registrar's own server for the registrant's actual contact details (historically .com/.net).

WHOIS

Who Is (legacy domain lookup protocol)

DNSSEC

Domain Name System Security Extensions - cryptographically signs DNS records so a resolver can verify a response hasn't been tampered with; signed independently at the registry/registrar level, separate from whether this app's own checks validate it.

DoH

DNS over HTTPS

DoT

DNS over TLS

HTTP

Hypertext Transfer Protocol

HTTPS

Hypertext Transfer Protocol Secure

NXDOMAIN

Non-Existent Domain - the DNS response code a resolver returns when a name has no records at all. This app's DNS-based availability check treats NXDOMAIN as a strong (though not certain) signal a domain is unregistered.

SERVFAIL

Server Failure - the DNS response code returned when a resolver couldn't complete a lookup (unreachable authoritative server, DNSSEC failure, etc.) - distinct from NXDOMAIN; this app treats it as inconclusive, not available.

Domain / TLD terms

TLD

Top-Level Domain

GTLD

Generic Top-Level Domain

CCTLD

Country Code Top-Level Domain

SLD

Second-Level Domain

FQDN

Fully Qualified Domain Name

NEW GTLD

New Generic Top-Level Domain (post-2012 ICANN expansion, e.g. .app, .dev)

STLD

Sponsored Top-Level Domain (restricted, e.g. .edu, .gov, .museum)

IDN

Internationalized Domain Name (non-ASCII characters, e.g. accented/non-Latin)

PUNYCODE

ASCII encoding of an IDN (e.g. xn--...) used at the DNS protocol level

APEX

Apex Domain (aka root domain, naked domain) - a domain used with no subdomain prefix (e.g. example.com, not www.example.com). Cannot hold a CNAME record at the zone apex, which is why "ALIAS"/"ANAME" records exist at some DNS providers.

DNS record types

TTL

Time To Live

IPv4 Address record

AAAA

IPv6 Address record

Mail Exchange record

Name Server record

CNAME

Canonical Name record

SOA

Start of Authority record

TXT

Text record

CAA

Certification Authority Authorization record - lets a domain owner restrict which Certificate Authorities are allowed to issue TLS certificates for it; most CAs check this before issuing a cert.

This app's own terms

PROVIDER

This app's term for which method checked a domain: DNS Check or RDAP

BUILD MODE

Which generator produced a search's domain list (e.g. cartesian, single_list, mangle)

SEARCH TYPE

Admin-configurable label/description shown for a build mode (Admin > Search Types)

WORD LIST

A named collection of words you control, used as Builder/Tool input

DAC

domain_availability_cache — this app's shared table of domain-check answers, reused across searches until expires_at passes

SEARCH RESULT

One row: a single generated domain name plus its availability answer within one search