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标准与规范

了解 URI, URL, and URN

url-300x197

  • URI:Uniform Resource Identifier,统一资源标识符;(RFC 3986)
  • URL:Uniform Resource Locator,统一资源定位符;(RFC 1738
  • URN:Uniform Resource Name,统一资源名称。(RFC 1737

URI可被视为定位符(URL),名称(URN)或两者兼备。统一资源名(URN)如同一个人的名称,而统一资源定位符(URL)代表一个人的住址。换言之,URN定义某事物的身份,而URL提供查找该事物的方法。

用于标识唯一书目的ISBN系统是一个典型的 URN 使用范例。例如,ISBN 0-486-27557-4(urn:isbn:0-486-27557-4)无二义性地标识出莎士比亚的戏剧《罗密欧与朱丽叶》的某一特定版本。

为获得该资源并阅读该书,人们需要它的位置,也就是一个 URL 地址。在类Unix操作系统中,一个典型的URL地址可能是一个文件目录,例如file:///home/username/RomeoAndJuliet.pdf。该URL标识出存储于本地硬盘中的电子书文件。因此,URL和URN有着互补的作用。

URL方案分类图。URL(定位符)和URN(名称)方案属于URI的子类,URI可以为URL或URN两者之一或同时是URI和URN。技术上讲,URL和URN属于资源ID;但是,人们往往无法将某种方案归类于两者中的某一个:所有的URI都可被作为名称看待,而某些方案同时体现了两者中的不同部分。


URI 标准

RFC3986,即“Uniform Resource Identifier (URI):Generic Syntax”,是一个 Internet Standard。 Request for Comments (RFC) 系列是著名的档案式文档系列,该系列构成了 Internet Engineering Task Force (IETF) 标准过程的主干。 在数以千计的 RFC 中,只有很少的部分,比如   TCP (RFC793) 以及 Internet Mail 格式 (RFC821) 和协议 (RFC822), 提高了整个 Internet Standard 的发展水平。 RFC3986 在  2005 年 1 月也提高了这个水平。

按照 URI 标准,上面的第一个例子 —— http://www.cisco.com/en/US/partners/index.html —— 实际上是一个 URI,并且它由以下几个组成部分:

th

  • 方案名 (http)

url(uniformresourcelocator)

  • 域名 (www.cisco.com)
  • 路径 (/en/US/partners/index.html)

thCA1OQ0FA

IETF 达成共识,共同管理该方案。Official IANA Registry of URI Schemes(请参阅 参考资料)中包括一些大家所熟悉的方案,如 httphttpsmailto,还有其他许多您可能熟悉或不熟悉的方案。

URI 路径像一个典型的文件路径名。URI 按照 UNIX® 的惯例采用了正下划线 (a/b/c),因为在 20 世纪 80 年代后期设计 URI 的时候, 在 Internet 上, UNIX 文化比 PC 文化更流行。正是那个时候,出现了几个用于访问远程文件的流行表示法。其中一个是 Ange-ftp, 它是用来编辑远程文件的 emacs 的一个扩展。它用路径名将主机名和用户名结合起来,以获取像/jbrown@freddie.ucla.edu:~mblack/这样的结果。为了跨机器进行命名,为 Web 开发的 URI 语法(按照非标准的 Apollo Domain UNIX)使用了双下划线符号,但是它也引入了方案语法,这样,来自许多不同协议的命名约定得到了统一。其中的一些例子有:

  • mailto:mbox@domain
  • ftp://host/file
  • http://domain/path

这里介绍的第二个例子是 www.yahoo.com/sports,它不是一个真正的 URI。 它是对 http://www.yahoo.com/sports 的一种方便的简写,是一种受流行的 Web 浏览器用户界面  (UI) 支持的格式。然而,不要再犯在 XSLT 中遗漏方案这样的错误,如下所示:

<xsl:include href="exslt.org/math/min/math.min.template.xsl" />

因为它将不会按照您期望的那样工作,除非您真的 在 XSLT 样式表之后引用 exslt.org 目录中的一个文件。XSLT 的 href 属性采用了一个 URI 引用,它可能是绝对引用,也可能是相对引用。以一个方案和一个冒号开始的 URI 引用是绝对引用;否则,该引用就是相对引用。相对的 URI 引用更像一个文件路径。例如,../noarch/config.xsd 也是一个相对的 URI 引用。

国际化的资源标志符

HTML 中的 href 属性采用了 URI 引用,这样讲有些过于简单。URI 和 URI 引用都是从有限的 ASCII 字符集合中得出的,并且 HTML 比它们更加国际化。事实上,对遵循 RFC3986 的注释的请求是符合 RFC3987 标准,即 Internationalized Resource Identifiers (IRI) 标准(请参阅 参考资料)。此规范在 IETF 标准化过程中没有它的前辈走的远,但是技术本身已是相当成熟,并被广泛部署。除了能够使用所有 Unicode 字符,而不是仅仅能够使用 ASCII 字符之外,IRI 和 URI 是完全一样的。像 URI一样,每个 IRI 都有一个相应的编码,以防需要在只接受 URI 的协议(比如 HTTP)中使用 IRI。

用 xml:base 重写基本 URI

通常, URI 引用与在哪种文档中发现它有关。如果使用基本 URI http://exslt.org/math/min/math.min.template.xsl 查看一个文档,并看到了一个 URI 引用 ../../random/random.xml,那么引用将扩展为 http://exslt.org/random/random.xml。在 HTML 中,您可以把一个 base 元素放在文档顶端来重写基本 URI。XML Base 规范(请参阅 参考资料)在 XML 中也提供了同样的功能。

考虑一个既可以用 file:/my/doc 访问也可以用 http://my.domain/doc 访问的文档。通常,当通过文件系统访问文档时,您可能希望这些引用像 #part2 那样扩展为 file:/my/doc#part2;而通过 HTTP 访问文档时,您可能希望 #part2 扩展为 http://my.domain/doc#part2。但是在 Resource Description Framework (RDF) 模式中,为了使一些组件正常工作,展开的形式必须保持不变。 XML Base 使这种扩展变得容易(参见清单 1)。

清单 1. RDF 中的展开形式

				
<rdf:RDF
  xmlns="&owl;"
  xmlns:owl="&owl;"
  xml:base="http://www.w3.org/2002/07/owl"
  xmlns:rdf="&rdf;"
  xmlns:rdfs="&rdfs;"
>
...
    <Class rdf:about="#Nothing"/>

在这个例子中,无论您是在哪里找到的那个文件,#Nothing 引用均被扩展为 http://www.w3.org/2002/07/owl#Nothing

好了,关于 URI、IRI 和 URI 引用的介绍就到此结束了。

URL 和 URN

设计 URI 的目的是让它起到名称和定位器的作用。当 IETF 用它们实现标准化的时候,它们就成了通常所说的 Uniform Resource Locators,并且另一项关于 Uniform Resource Names 的独立的工作也已经开始了。

对于 Internet 主机,名称和位置都有单独的标准。主机名和域名有相同的语法(例如,zork1.example.edu)。这些主机名通过 Domain Name System (DNS) 协议和类似 192.168.300.21 的地址相连。当主机改变了在网络中的位置或重新编号之后,这种间接的做法允许主机保留其名称。

Web 中偶尔中断的链接使 Web 地址从外观上看更像是一个位置,而不是一个名称,并且在 IEIF 社区中也出现了不同的观点:

  • URI:RFC1630,发布于 1994 年 6 月,被称为“Universal Resource Identifiers in WWW: A Unifying Syntax for the Expression of Names and Addresses of Objects on the Network as used in the World-Wide Web”(请参阅 参考资料)。它是一个Informational RFC  —— 也就是说,它没有获得社区的任何认可。
  • URL:RFC1738,发布于 1994 年 12 月, 被称为“Uniform Resource Locators”(请参阅 参考资料)。它是一个 Proposed Standard —— 也就是说,它是一个共识过程的结果,虽然它还没有经过测试,并成熟到足以成为一个完整的 Internet Standard。
  • URN:RFC1737,发布于 1994 年 12 月,被称为“Functional Requirements for Uniform Resource Names”(请参阅 参考资料)。

1997 年,紧随 Proposed Standard RFC2141(即 URN Syntax)之后发布了 RFC1737,它指定了另一个方案 —— urn: —— 来加入 http:ftp:和其他协议中。

最终的 URI Standard (RFC3986) 在 1.1.3 小节“URI, URL, and URN”中澄清了这一区别:

URI 可以进一步分为定位器、名称,或者二者兼具。术语“Uniform Resource Locator” (URL) 涉及的是 URI 的子集,除识别资源外,它还通过描述其最初访问机制(比如它的网络“位置”)来提供定位资源的方法。 术语“Uniform Resource Name” (URN) 在历史上曾用于引用“urn”方案 [RFC2141] 下的 URI,这个 URI 需要是全球惟一的,并且在资源不存在或不再可用时依然保持不变,对于其他任何拥有名称的一些属性的 URI,都需要使用这样的 URI。

对于单独的方案,没有必要将其分为仅仅是一个 “名称”或者是一个“定位器”。 来自任意特定方案的 URI 实例可能有名称或定位器的特征,或两者兼而有之, 这通常取决于标识符分配中的持久性和命名机构对其关注程度, 而不取决于其他方案的质量。未来的规范和相关的文档应当使用通用术语“URI”,而不是使用有更多限制的条目“URL”和“URN” [RFC3305]。

http://www.ibm.com/developerworks/cn/xml/x-urlni.html

 

附录(梳理归类):

其中,URL,URN是URI的子集,其区别如下: Web上地址的基本形式是URI,它代表统一资源标识符,有两种形式: URL:目前URI的最普遍形式就是无处不在的URL或统一资源定位器。 URN:URL的一种更新形式,统一资源名称(URN, Uniform Resource Name)不依赖于位置,并且有可能减少失效连接的个数。但是其流行还需假以时日,因为它需要更精密软件的支持。

参考:http://www.cnlei.org/blog/article.asp?id=356

URN 站点 : http://purl.org/ | http://www.doi.org/demos.html

 

[文章部分内容引用地址] :

http://blog.sina.com.cn/s/blog_5c4a1a800100gxke.html

[分清 URI、URL 和 URN] http://www.ibm.com/developerworks/cn/xml/x-urlni.html

 

P.S. :  http://,https://,mms://,ftp://,rtsp://,ssl://,sftp://,pnm://,rtmp://等协议, 又如 thunder迅雷 , flashget快车 &&QQ旋风等.

thunder://类似的协议是base64编码加密。

 

Special-Use Domain Names

  • Created

2012-07-06

  • Last Updated

2013-02-21

Special-Use Domain Names

Registration Procedure(s)
Standards Action and IESG Approval
Reference
[RFC6761]
Note
The "Special Use" designation applies to both the listed domains and their subdomains.
Alternative Formats
CSV      Plain text
Name Reference
10.in-addr.arpa. [RFC6761]
16.172.in-addr.arpa. [RFC6761]
17.172.in-addr.arpa. [RFC6761]
18.172.in-addr.arpa. [RFC6761]
19.172.in-addr.arpa. [RFC6761]
20.172.in-addr.arpa. [RFC6761]
21.172.in-addr.arpa. [RFC6761]
22.172.in-addr.arpa. [RFC6761]
23.172.in-addr.arpa. [RFC6761]
24.172.in-addr.arpa. [RFC6761]
25.172.in-addr.arpa. [RFC6761]
26.172.in-addr.arpa. [RFC6761]
27.172.in-addr.arpa. [RFC6761]
28.172.in-addr.arpa. [RFC6761]
29.172.in-addr.arpa. [RFC6761]
30.172.in-addr.arpa. [RFC6761]
31.172.in-addr.arpa. [RFC6761]
168.192.in-addr.arpa. [RFC6761]
254.169.in-addr.arpa. [RFC6762]
8.e.f.ip6.arpa. [RFC6762]
9.e.f.ip6.arpa. [RFC6762]
a.e.f.ip6.arpa. [RFC6762]
b.e.f.ip6.arpa. [RFC6762]
example. [RFC6761]
example.com. [RFC6761]
example.net. [RFC6761]
example.org. [RFC6761]
invalid. [RFC6761]
local. [RFC6762]
localhost. [RFC6761]
test. [RFC6761]

文件大小换算

1 Mio file = 1 mebioctet* = 220 octets = 1,024 Kio = 1,048,576 octets
10 Mio file = 10 mebioctet = 10 x 220 octets = 10,240 Kio = 10,485,760 octets
100 Mio file = 100 mebioctet = 100 x 220 octets = 102,400 Kio = 104,857,600 octets
1 Gio file = 1 gibioctet = 230 octets = 1,024 Mio = 1,073,741,824 octets
10 Gio file = 10 gibioctet = 10 x 230 octets = 10,240 Mio = 10,737,418,240 octets

1 Mbit file = 1 megabit = 106 bits = 1,000 kbit = 1,000,000 bits
10 Mbit file = 10 megabit = 107 bits = 10,000 kbit = 10,000,000 bits
100 Mbit file = 100 megabit = 108 bits = 100,000 kbit = 100,000,000 bits
1 Gbit file = 1 gigabit = 109 bits = 1,000 Mbit = 1,000,000,000 bits
10 Gbit file = 10 gigabit = 1010 bits = 10,000 Mbit = 10,000,000,000 bits

 

国际化域名IDN (Internationalized Domain Names) 转换

将域名国际化 IDN (internationalized domain name) 标准编码的域名标签的子字符串解码为一个 Unicode 字符串(Punycode). 或者将一个国际化域名字符串(Punycode )转换为符合 IDN 标准的域名
例:
Bücher.ch --> xn--bcher-kva.ch |
новини.com --> xn--b1amarcd.com |
统计局.中国 --> xn--dgtp91f7xi.xn--fiqs8s |
xn--j6w193g.xn--fiqs8s --> 香港.中国

代码段:

IDNA  >> Punycode

IdnMapping idn = new IdnMapping();
string international = idn.GetAscii(yourDomain, 0, yourDomain.Length);

Punycode  >> IDNA

>IdnMapping idn = new IdnMapping();
string nonInternational = idn.GetUnicode(yourDomain, 0, yourDomain.Length);

 

下载文件 : IDN Converter

 

IANA IPv4 地址空间注册表

IANA IPv4 Address Space Registry

Last Updated
2013-03-22
Description
The allocation of Internet Protocol version 4 (IPv4) address space to various registries is listed
here. Originally, all the IPv4 address spaces was managed directly by the IANA. Later parts of the
address space were allocated to various other registries to manage for particular purposes or
regional areas of the world. RFC 1466 [RFC1466] documents most of these allocations.

This registry is also available in plain text.

Prefix Designation Date Whois Status [1] Note
000/8 IANA – Local Identification 1981-09 RESERVED [2]
001/8 APNIC 2010-01 whois.apnic.net ALLOCATED
002/8 RIPE NCC 2009-09 whois.ripe.net ALLOCATED
003/8 General Electric Company 1994-05 LEGACY
004/8 Level 3 Communications, Inc. 1992-12 LEGACY
005/8 RIPE NCC 2010-11 whois.ripe.net ALLOCATED
006/8 Army Information Systems Center 1994-02 LEGACY
007/8 Administered by ARIN 1995-04 whois.arin.net LEGACY
008/8 Level 3 Communications, Inc. 1992-12 LEGACY
009/8 IBM 1992-08 LEGACY
010/8 IANA – Private Use 1995-06 RESERVED [3]
011/8 DoD Intel Information Systems 1993-05 LEGACY
012/8 AT&T Bell Laboratories 1995-06 LEGACY
013/8 Xerox Corporation 1991-09 LEGACY
014/8 APNIC 2010-04 whois.apnic.net ALLOCATED [4]
015/8 Hewlett-Packard Company 1994-07 LEGACY
016/8 Digital Equipment Corporation 1994-11 LEGACY
017/8 Apple Computer Inc. 1992-07 LEGACY
018/8 MIT 1994-01 LEGACY
019/8 Ford Motor Company 1995-05 LEGACY
020/8 Computer Sciences Corporation 1994-10 LEGACY
021/8 DDN-RVN 1991-07 LEGACY
022/8 Defense Information Systems Agency 1993-05 LEGACY
023/8 ARIN 2010-11 whois.arin.net ALLOCATED
024/8 ARIN 2001-05 whois.arin.net ALLOCATED
025/8 UK Ministry of Defence 1995-01 whois.ripe.net LEGACY
026/8 Defense Information Systems Agency 1995-05 LEGACY
027/8 APNIC 2010-01 whois.apnic.net ALLOCATED
028/8 DSI-North 1992-07 LEGACY
029/8 Defense Information Systems Agency 1991-07 LEGACY
030/8 Defense Information Systems Agency 1991-07 LEGACY
031/8 RIPE NCC 2010-05 whois.ripe.net ALLOCATED
032/8 AT&T Global Network Services 1994-06 LEGACY
033/8 DLA Systems Automation Center 1991-01 LEGACY
034/8 Halliburton Company 1993-03 LEGACY
035/8 Administered by ARIN 1994-04 whois.arin.net LEGACY
036/8 APNIC 2010-10 whois.apnic.net ALLOCATED
037/8 RIPE NCC 2010-11 whois.ripe.net ALLOCATED
038/8 PSINet, Inc. 1994-09 LEGACY
039/8 APNIC 2011-01 whois.apnic.net ALLOCATED
040/8 Administered by ARIN 1994-06 whois.arin.net LEGACY
041/8 AFRINIC 2005-04 whois.afrinic.net ALLOCATED
042/8 APNIC 2010-10 whois.apnic.net ALLOCATED
043/8 Administered by APNIC 1991-01 whois.apnic.net LEGACY
044/8 Amateur Radio Digital Communications 1992-07 LEGACY
045/8 Administered by ARIN 1995-01 whois.arin.net LEGACY
046/8 RIPE NCC 2009-09 whois.ripe.net ALLOCATED
047/8 Administered by ARIN 1991-01 whois.arin.net LEGACY
048/8 Prudential Securities Inc. 1995-05 LEGACY
049/8 APNIC 2010-08 whois.apnic.net ALLOCATED
050/8 ARIN 2010-02 whois.arin.net ALLOCATED
051/8 UK Government Department for Work and Pensions 1994-08 whois.ripe.net LEGACY
052/8 E.I. duPont de Nemours and Co., Inc. 1991-12 LEGACY
053/8 Cap Debis CCS 1993-10 LEGACY
054/8 Administered by ARIN 1992-03 whois.arin.net LEGACY
055/8 DoD Network Information Center 1995-04 LEGACY
056/8 US Postal Service 1994-06 LEGACY
057/8 SITA 1995-05 LEGACY
058/8 APNIC 2004-04 whois.apnic.net ALLOCATED
059/8 APNIC 2004-04 whois.apnic.net ALLOCATED
060/8 APNIC 2003-04 whois.apnic.net ALLOCATED
061/8 APNIC 1997-04 whois.apnic.net ALLOCATED
062/8 RIPE NCC 1997-04 whois.ripe.net ALLOCATED
063/8 ARIN 1997-04 whois.arin.net ALLOCATED
064/8 ARIN 1999-07 whois.arin.net ALLOCATED
065/8 ARIN 2000-07 whois.arin.net ALLOCATED
066/8 ARIN 2000-07 whois.arin.net ALLOCATED
067/8 ARIN 2001-05 whois.arin.net ALLOCATED
068/8 ARIN 2001-06 whois.arin.net ALLOCATED
069/8 ARIN 2002-08 whois.arin.net ALLOCATED
070/8 ARIN 2004-01 whois.arin.net ALLOCATED
071/8 ARIN 2004-08 whois.arin.net ALLOCATED
072/8 ARIN 2004-08 whois.arin.net ALLOCATED
073/8 ARIN 2005-03 whois.arin.net ALLOCATED
074/8 ARIN 2005-06 whois.arin.net ALLOCATED
075/8 ARIN 2005-06 whois.arin.net ALLOCATED
076/8 ARIN 2005-06 whois.arin.net ALLOCATED
077/8 RIPE NCC 2006-08 whois.ripe.net ALLOCATED
078/8 RIPE NCC 2006-08 whois.ripe.net ALLOCATED
079/8 RIPE NCC 2006-08 whois.ripe.net ALLOCATED
080/8 RIPE NCC 2001-04 whois.ripe.net ALLOCATED
081/8 RIPE NCC 2001-04 whois.ripe.net ALLOCATED
082/8 RIPE NCC 2002-11 whois.ripe.net ALLOCATED
083/8 RIPE NCC 2003-11 whois.ripe.net ALLOCATED
084/8 RIPE NCC 2003-11 whois.ripe.net ALLOCATED
085/8 RIPE NCC 2004-04 whois.ripe.net ALLOCATED
086/8 RIPE NCC 2004-04 whois.ripe.net ALLOCATED
087/8 RIPE NCC 2004-04 whois.ripe.net ALLOCATED
088/8 RIPE NCC 2004-04 whois.ripe.net ALLOCATED
089/8 RIPE NCC 2005-06 whois.ripe.net ALLOCATED
090/8 RIPE NCC 2005-06 whois.ripe.net ALLOCATED
091/8 RIPE NCC 2005-06 whois.ripe.net ALLOCATED
092/8 RIPE NCC 2007-03 whois.ripe.net ALLOCATED
093/8 RIPE NCC 2007-03 whois.ripe.net ALLOCATED
094/8 RIPE NCC 2007-07 whois.ripe.net ALLOCATED
095/8 RIPE NCC 2007-07 whois.ripe.net ALLOCATED
096/8 ARIN 2006-10 whois.arin.net ALLOCATED
097/8 ARIN 2006-10 whois.arin.net ALLOCATED
098/8 ARIN 2006-10 whois.arin.net ALLOCATED
099/8 ARIN 2006-10 whois.arin.net ALLOCATED
100/8 ARIN 2010-11 whois.arin.net ALLOCATED [5]
101/8 APNIC 2010-08 whois.apnic.net ALLOCATED
102/8 AFRINIC 2011-02 whois.afrinic.net ALLOCATED
103/8 APNIC 2011-02 whois.apnic.net ALLOCATED
104/8 ARIN 2011-02 whois.arin.net ALLOCATED
105/8 AFRINIC 2010-11 whois.afrinic.net ALLOCATED
106/8 APNIC 2011-01 whois.apnic.net ALLOCATED
107/8 ARIN 2010-02 whois.arin.net ALLOCATED
108/8 ARIN 2008-12 whois.arin.net ALLOCATED
109/8 RIPE NCC 2009-01 whois.ripe.net ALLOCATED
110/8 APNIC 2008-11 whois.apnic.net ALLOCATED
111/8 APNIC 2008-11 whois.apnic.net ALLOCATED
112/8 APNIC 2008-05 whois.apnic.net ALLOCATED
113/8 APNIC 2008-05 whois.apnic.net ALLOCATED
114/8 APNIC 2007-10 whois.apnic.net ALLOCATED
115/8 APNIC 2007-10 whois.apnic.net ALLOCATED
116/8 APNIC 2007-01 whois.apnic.net ALLOCATED
117/8 APNIC 2007-01 whois.apnic.net ALLOCATED
118/8 APNIC 2007-01 whois.apnic.net ALLOCATED
119/8 APNIC 2007-01 whois.apnic.net ALLOCATED
120/8 APNIC 2007-01 whois.apnic.net ALLOCATED
121/8 APNIC 2006-01 whois.apnic.net ALLOCATED
122/8 APNIC 2006-01 whois.apnic.net ALLOCATED
123/8 APNIC 2006-01 whois.apnic.net ALLOCATED
124/8 APNIC 2005-01 whois.apnic.net ALLOCATED
125/8 APNIC 2005-01 whois.apnic.net ALLOCATED
126/8 APNIC 2005-01 whois.apnic.net ALLOCATED
127/8 IANA – Loopback 1981-09 RESERVED [6]
128/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
129/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
130/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
131/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
132/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
133/8 Administered by APNIC 1997-03 whois.apnic.net LEGACY
134/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
135/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
136/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
137/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
138/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
139/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
140/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
141/8 Administered by RIPE NCC 1993-05 whois.ripe.net LEGACY
142/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
143/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
144/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
145/8 Administered by RIPE NCC 1993-05 whois.ripe.net LEGACY
146/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
147/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
148/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
149/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
150/8 Administered by APNIC 1993-05 whois.apnic.net LEGACY
151/8 Administered by RIPE NCC 1993-05 whois.ripe.net LEGACY
152/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
153/8 Administered by APNIC 1993-05 whois.apnic.net LEGACY
154/8 Administered by AFRINIC 1993-05 whois.afrinic.net LEGACY
155/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
156/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
157/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
158/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
159/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
160/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
161/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
162/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
163/8 Administered by APNIC 1993-05 whois.apnic.net LEGACY
164/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
165/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
166/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
167/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
168/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
169/8 Administered by ARIN 1993-05 whois.arin.net LEGACY [7]
170/8 Administered by ARIN 1993-05 whois.arin.net LEGACY
171/8 Administered by APNIC 1993-05 whois.apnic.net LEGACY
172/8 Administered by ARIN 1993-05 whois.arin.net LEGACY [8]
173/8 ARIN 2008-02 whois.arin.net ALLOCATED
174/8 ARIN 2008-02 whois.arin.net ALLOCATED
175/8 APNIC 2009-08 whois.apnic.net ALLOCATED
176/8 RIPE NCC 2010-05 whois.ripe.net ALLOCATED
177/8 LACNIC 2010-06 whois.lacnic.net ALLOCATED
178/8 RIPE NCC 2009-01 whois.ripe.net ALLOCATED
179/8 LACNIC 2011-02 whois.lacnic.net ALLOCATED
180/8 APNIC 2009-04 whois.apnic.net ALLOCATED
181/8 LACNIC 2010-06 whois.lacnic.net ALLOCATED
182/8 APNIC 2009-08 whois.apnic.net ALLOCATED
183/8 APNIC 2009-04 whois.apnic.net ALLOCATED
184/8 ARIN 2008-12 whois.arin.net ALLOCATED
185/8 RIPE NCC 2011-02 whois.ripe.net ALLOCATED
186/8 LACNIC 2007-09 whois.lacnic.net ALLOCATED
187/8 LACNIC 2007-09 whois.lacnic.net ALLOCATED
188/8 Administered by RIPE NCC 1993-05 whois.ripe.net LEGACY
189/8 LACNIC 1995-06 whois.lacnic.net ALLOCATED
190/8 LACNIC 1995-06 whois.lacnic.net ALLOCATED
191/8 Administered by LACNIC 1993-05 whois.lacnic.net LEGACY
192/8 Administered by ARIN 1993-05 whois.arin.net LEGACY [9][10]
193/8 RIPE NCC 1993-05 whois.ripe.net ALLOCATED
194/8 RIPE NCC 1993-05 whois.ripe.net ALLOCATED
195/8 RIPE NCC 1993-05 whois.ripe.net ALLOCATED
196/8 Administered by AFRINIC 1993-05 whois.afrinic.net LEGACY
197/8 AFRINIC 2008-10 whois.afrinic.net ALLOCATED
198/8 Administered by ARIN 1993-05 whois.arin.net LEGACY [11]
199/8 ARIN 1993-05 whois.arin.net ALLOCATED
200/8 LACNIC 2002-11 whois.lacnic.net ALLOCATED
201/8 LACNIC 2003-04 whois.lacnic.net ALLOCATED
202/8 APNIC 1993-05 whois.apnic.net ALLOCATED
203/8 APNIC 1993-05 whois.apnic.net ALLOCATED [12]
204/8 ARIN 1994-03 whois.arin.net ALLOCATED
205/8 ARIN 1994-03 whois.arin.net ALLOCATED
206/8 ARIN 1995-04 whois.arin.net ALLOCATED
207/8 ARIN 1995-11 whois.arin.net ALLOCATED
208/8 ARIN 1996-04 whois.arin.net ALLOCATED
209/8 ARIN 1996-06 whois.arin.net ALLOCATED
210/8 APNIC 1996-06 whois.apnic.net ALLOCATED
211/8 APNIC 1996-06 whois.apnic.net ALLOCATED
212/8 RIPE NCC 1997-10 whois.ripe.net ALLOCATED
213/8 RIPE NCC 1993-10 whois.ripe.net ALLOCATED
214/8 US-DOD 1998-03 LEGACY
215/8 US-DOD 1998-03 LEGACY
216/8 ARIN 1998-04 whois.arin.net ALLOCATED
217/8 RIPE NCC 2000-06 whois.ripe.net ALLOCATED
218/8 APNIC 2000-12 whois.apnic.net ALLOCATED
219/8 APNIC 2001-09 whois.apnic.net ALLOCATED
220/8 APNIC 2001-12 whois.apnic.net ALLOCATED
221/8 APNIC 2002-07 whois.apnic.net ALLOCATED
222/8 APNIC 2003-02 whois.apnic.net ALLOCATED
223/8 APNIC 2010-04 whois.apnic.net ALLOCATED
224/8 Multicast 1981-09 RESERVED [13]
225/8 Multicast 1981-09 RESERVED [13]
226/8 Multicast 1981-09 RESERVED [13]
227/8 Multicast 1981-09 RESERVED [13]
228/8 Multicast 1981-09 RESERVED [13]
229/8 Multicast 1981-09 RESERVED [13]
230/8 Multicast 1981-09 RESERVED [13]
231/8 Multicast 1981-09 RESERVED [13]
232/8 Multicast 1981-09 RESERVED [13]
233/8 Multicast 1981-09 RESERVED [13]
234/8 Multicast 1981-09 RESERVED [13][14]
235/8 Multicast 1981-09 RESERVED [13]
236/8 Multicast 1981-09 RESERVED [13]
237/8 Multicast 1981-09 RESERVED [13]
238/8 Multicast 1981-09 RESERVED [13]
239/8 Multicast 1981-09 RESERVED [13][15]
240/8 Future use 1981-09 RESERVED [16]
241/8 Future use 1981-09 RESERVED [16]
242/8 Future use 1981-09 RESERVED [16]
243/8 Future use 1981-09 RESERVED [16]
244/8 Future use 1981-09 RESERVED [16]
245/8 Future use 1981-09 RESERVED [16]
246/8 Future use 1981-09 RESERVED [16]
247/8 Future use 1981-09 RESERVED [16]
248/8 Future use 1981-09 RESERVED [16]
249/8 Future use 1981-09 RESERVED [16]
250/8 Future use 1981-09 RESERVED [16]
251/8 Future use 1981-09 RESERVED [16]
252/8 Future use 1981-09 RESERVED [16]
253/8 Future use 1981-09 RESERVED [16]
254/8 Future use 1981-09 RESERVED [16]
255/8 Future use 1981-09 RESERVED [16][17]

Footnotes

[1]
Indicates the status of address blocks as follows:
RESERVED: designated by the IETF for specific non-global-unicast purposes as noted.
LEGACY: allocated by the central Internet Registry (IR) prior to the Regional Internet Registries
(RIRs). This address space is now administered by individual RIRs as noted, including maintenance
of WHOIS Directory and reverse DNS records. Assignments from these blocks are distributed globally
on a regional basis.
ALLOCATED: delegated entirely to specific RIR as indicated.
UNALLOCATED: not yet allocated or reserved.
[2]
0.0.0.0/8 reserved for self-identification [RFC1122], section 3.2.1.3. 
Reserved by protocol. For authoritative registration, see [IANA registry iana-ipv4-special-registry].
[3]
Reserved for Private-Use Networks [RFC1918].
Complete registration details for 10.0.0.0/8 are found in [IANA registry iana-ipv4-special-registry].
[4]
This was reserved for Public Data Networks [RFC1356]. See [IANA registry public-data-network-numbers].
It was recovered in February 2008 and was subsequently allocated to APNIC in April 2010.
[5]
100.64.0.0/10 reserved for Shared Address Space [RFC6598]. 
Complete registration details for 100.64.0.0/10 are found in [IANA registry iana-ipv4-special-registry].
[6]
127.0.0.0/8 reserved for Loopback [RFC1122], section 3.2.1.3. 
Reserved by protocol. For authoritative registration, see [IANA registry iana-ipv4-special-registry].
[7]
169.254.0.0/16 reserved for Link Local [RFC3927].
Reserved by protocol. For authoritative registration, see [IANA registry iana-ipv4-special-registry].
[8]
172.16.0.0/12 reserved for Private-Use Networks [RFC1918]. 
Complete registration details are found in [IANA registry iana-ipv4-special-registry].
[9]
192.0.2.0/24  reserved for TEST-NET-1 [RFC5737]. 
Complete registration details for 192.0.2.0/24 are found in [IANA registry iana-ipv4-special-registry].
192.88.99.0/24 reserved for 6to4 Relay Anycast [RFC3068]
Complete registration details for 192.88.99.0/24 are found in [IANA registry iana-ipv4-special-registry].
192.88.99.2/32 reserved for 6a44 Relay Anycast [RFC6751] (possibly collocated with 6to4 Relay 
at 192.88.99.1/32 - see [RFC3068] section 2.4)
192.168.0.0/16 reserved for Private-Use Networks [RFC1918]. 
Complete registration details for 192.168.0.0/16 are found in [IANA registry iana-ipv4-special-registry].
[10]
192.0.0.0/24 reserved for IANA IPv4 Special Purpose Address Registry [RFC5736]. 
Complete registration details for 192.0.0.0/24 are found in [IANA registry iana-ipv4-special-registry].
[11]
198.18.0.0/15 reserved for Network Interconnect Device Benchmark Testing [RFC2544]. 
Complete registration details for 198.18.0.0/15 are found in [IANA registry iana-ipv4-special-registry].
198.51.100.0/24 reserved for TEST-NET-2 [RFC5737]. 
Complete registration details for 198.51.100.0/24 are found in [IANA registry iana-ipv4-special-registry].
[12]
203.0.113.0/24 reserved for TEST-NET-3 [RFC5737]. 
Complete registration details for 203.0.113.0/24 are found in [IANA registry iana-ipv4-special-registry].
[13]
Multicast (formerly "Class D") [RFC5771] registered in [IANA registry multicast-addresses]
[14]
Unicast-Prefix-Based IPv4 Multicast Addresses [RFC6034]
[15]
Administratively Scoped IP Multicast [RFC2365]
[16]
Reserved for future use (formerly "Class E") [RFC1112].
Reserved by protocol. For authoritative registration, see [IANA registry iana-ipv4-special-registry].
[17]
255.255.255.255 is reserved for "limited broadcast" destination address [RFC919] and [RFC922].
Complete registration details for 255.255.255.255/32 are found in [IANA registry iana-ipv4-special-registry].

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