URL 各部分的名称和最大长度 [英] Names and maximum lengths of the parts of a URL

问题描述

在此网址中:

http://www.subdomain.domainname.abc.xyz.com.us/directory/filename.extension

1. 每个部分的名称是什么?
2. 每个部分的最大长度是多少?例如子域、域名、顶级域……

解决方案

子域<的维基百科条目/a> 回答这两个问题:

1. 每个部分的名称是什么?

<块引用>

子域是属于更大域的域；唯一不是子域的域是 根域.例如，west.example.com 和 east.example.com 是 example.com 域的子域，而后者又是一个子域com 顶级域 (TLD).子域"表示相对依赖，而不是绝对依赖:例如，wikipedia.org 包含 org 域的子域，en.wikipedia.org 包含域 wikipedia.org 的子域.

2. 每个部分的最大长度是多少?例如子域，域名，顶级域名……

<块引用>

理论上这个细分可以下降到 127 层深，每个 DNS 标签可以包含最多 63 个字符，只要整个域名的总长度不超过 255 个字符.但实际上，大多数域名注册管理机构都限制为 253 个字符.

In this URL:

http://www.subdomain.domainname.abc.xyz.com.us/directory/filename.extension

1. What is the name of each part?
2. What is maximum length of each part? e.g. subdomain, domain name, top-level domain…

解决方案

The Wikipedia entry for Subdomain answers both questions:

1. What is the name of each part?

A subdomain is a domain that is part of a larger domain; the only domain that is not also a subdomain is the root domain. For example, west.example.com and east.example.com are subdomains of the example.com domain, which in turn is a subdomain of the com top-level domain (TLD). A "subdomain" expresses relative dependence, not absolute dependence: for example, wikipedia.org comprises a subdomain of the org domain, and en.wikipedia.org comprises a subdomain of the domain wikipedia.org.

2. What is maximum length of each part? e.g. subdomain, domain name, top-level domain…

In theory this subdivision can go down to 127 levels deep, and each DNS label can contain up to 63 characters, as long as the whole domain name does not exceed a total length of 255 characters. But in practice most domain registries limit at 253 characters.

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