TLDの種類と分類
トップレベルドメインの分類方法 — gTLD、ccTLD、sTLD、新gTLDプログラムについて説明します。
TLD（トップレベルドメイン）
The last segment of a domain name (e.g., .com, .org, .uk).
gTLD（汎用トップレベルドメイン）
Top-level domain with 3+ characters not tied to a specific country.
ccTLD（国別コードトップレベルドメイン）
Two-letter TLD assigned to a specific country or territory.
新gTLD（新しい汎用トップレベルドメイン）
Generic top-level domains introduced through ICANN's 2012+ New gTLD Program.
レガシーTLD
Original gTLDs (.com, .net, .org) that predate the New gTLD Program.
sTLD（スポンサー付きトップレベルドメイン）
Specialized TLD with eligibility requirements, managed by a sponsoring organization.
ブランドTLD（.brand）
New gTLD using a company's brand name, operated exclusively by that company.
地理的TLD（GeoTLD）
New gTLD representing a geographic region (city, state, or territory).
IDN TLD（国際化ドメイン名TLD）
TLD written in non-Latin scripts (Arabic, Chinese, Cyrillic, etc.).
SLD（セカンドレベルドメイン）
The part of a domain name directly left of the TLD (e.g., 'example' in example.com).
FQDN（完全修飾ドメイン名）
Complete domain name with all labels from host to TLD (e.g., www.example.com.).
制限付きTLD
TLD that limits registration to eligible organizations or individuals.
インフラストラクチャTLD（.arpa）
Special-purpose TLD (.arpa) reserved exclusively for DNS infrastructure and protocol use.
予約済みテストTLD
IANA-reserved TLDs (.test, .example, .invalid, .localhost) guaranteed never to resolve in the public DNS.
TLDオペレーター（レジストリオペレーター）
Entity authorized by ICANN to administer all domain registrations within a specific TLD.
委任済みTLD
TLD formally added to the DNS root zone by IANA and resolvable on the public internet.
ASCII TLD
TLD composed entirely of ASCII characters, natively compatible with all DNS software without encoding.
オープンTLD
TLD with unrestricted registration policies open to any person or entity worldwide.
コミュニティTLD
TLD designed to serve a specific community of interest with eligibility restrictions and community-aligned policies.
汎用制限TLD
Legacy gTLDs (.biz, .name, .pro) intended for specific uses but with limited enforcement of registration restrictions.
TLD文字列
The proposed character sequence for a new TLD, evaluated by ICANN for similarity, geography, and conflicts.
ドットブランドTLD（.brand）
Company-operated new gTLD using a brand name as the extension, unavailable for public registration.