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域名系统 (Domain Name System, DNS) 帮助用户浏览互联网。互联网上的每台设备都有一个唯一地址,即互联网协议 (Internet Protocol, IP) 地址。IP 地址可能很难记忆。DNS 通过允许使用基于文本的域名来代替 IP 地址,使互联网的使用变得更加便利。

IP 地址

每台联网设备都有一个唯一的 IP 地址。IP 地址由一系列的数字和字母构成。例如,ICANN 网站的 IP 地址是。



域名系统 (DNS)

DNS 将 IP 地址与域名联系起来,帮助用户浏览互联网。

如果您想访问 ICANN 网站,您只需在浏览器中输入""。您的设备使用 DNS 查询域名并找到其相关的 IP 地址。DNS 是互联网的地址簿。

DNS 的信息图表

如果您想深入了解该系统的运作方式,请查看 ICANN 组织提供的 DNS 的信息图表

Domain Name System
Internationalized Domain Name ,IDN,"IDNs are domain names that include characters used in the local representation of languages that are not written with the twenty-six letters of the basic Latin alphabet ""a-z"". An IDN can contain Latin letters with diacritical marks, as required by many European languages, or may consist of characters from non-Latin scripts such as Arabic or Chinese. Many languages also use other types of digits than the European ""0-9"". The basic Latin alphabet together with the European-Arabic digits are, for the purpose of domain names, termed ""ASCII characters"" (ASCII = American Standard Code for Information Interchange). These are also included in the broader range of ""Unicode characters"" that provides the basis for IDNs. The ""hostname rule"" requires that all domain names of the type under consideration here are stored in the DNS using only the ASCII characters listed above, with the one further addition of the hyphen ""-"". The Unicode form of an IDN therefore requires special encoding before it is entered into the DNS. The following terminology is used when distinguishing between these forms: A domain name consists of a series of ""labels"" (separated by ""dots""). The ASCII form of an IDN label is termed an ""A-label"". All operations defined in the DNS protocol use A-labels exclusively. The Unicode form, which a user expects to be displayed, is termed a ""U-label"". The difference may be illustrated with the Hindi word for ""test"" — परीका — appearing here as a U-label would (in the Devanagari script). A special form of ""ASCII compatible encoding"" (abbreviated ACE) is applied to this to produce the corresponding A-label: xn--11b5bs1di. A domain name that only includes ASCII letters, digits, and hyphens is termed an ""LDH label"". Although the definitions of A-labels and LDH-labels overlap, a name consisting exclusively of LDH labels, such as"""" is not an IDN."