---
id: "second-level-domain"
kind: "glossary-term"
title: "二级域"
language: "zh-Hans"
category: "TLD类型与计划"
updated: "2026-10-10T12:00:00Z"
canonical: "https://tldlog.com/zh/cihui/erjiyu/"
translations:
  en: "https://tldlog.com/glossary/second-level-domain/"
  es: "https://tldlog.com/es/glosario/dominio-segundo-nivel/"
  de: "https://tldlog.com/de/glossar/second-level-domain/"
  fr: "https://tldlog.com/fr/glossaire/domaine-second-niveau/"
  it: "https://tldlog.com/it/glossario/dominio-secondo-livello/"
  pt-BR: "https://tldlog.com/pt/glossario/dominio-segundo-nivel/"
  ru: "https://tldlog.com/ru/glossariy/domen-vtorogo-urovnya/"
---

# 二级域

域名中紧挨在TLD左侧的部分，例如example.com中的example。人们注册和付费的通常就是这一部分。有些ccTLD使用固定的二级域，例如.co.uk，因此域名在低一级的层级注册。

## 相关术语

- [TLD](https://tldlog.com/zh/cihui/tld/)
- [域名](https://tldlog.com/zh/cihui/yuming/)
- [子域名](https://tldlog.com/zh/cihui/ziyuming/)