DNS不允许使用下划线
2013-02-22DNS不允许有下划线,参照RFC1034（http://www.ietf.org/rfc/rfc1034.txt）,标准域名：
不允许有下划线。
第一部分可以是国际化域名，但不可以短划线开始或结束
不允许使用下划线字符。
不允许使用空格。
不区分大小写。
最终的字符串编码连同’.com’或’.net’后缀不得超过67个字符。
1、堪称世界上最长的字母域名(63位)
www.ihavenottheshortestdomainnameintheworldsoiregisterthelongestone.com
2、最长的数字域名(圆周率小数点后的63位数字组成)
www.141592653589793238462643383279502884197169399375105820974944592.eu
3、最长的数字域名(67位)
www.1111111111111111111111111111111111111111111111111111111111111111111.com
4、另一个叫AZ的人注册的域名(63个字符)
www.thelongestdomainintheworldandthensomeandthensomemoreandmore.com
5、一个德国最长域名
www.thisisthelongesteuropeandomainnameallovertheworldandnowitismine.eu
6、进入后看到的是百度页面，但是指向的IP不是百度的
www.mamashuojiusuannizhucedeyumingzaichangbaidudounengsousuochulai.cn
7、很长的CN域名，全部是01码
www.101010101010101010101010101010101010101010101010101010101010101.cn
8、另一个比较长的CN域名，也能访问
www.shuishuowoyumingbugouchangabaudugoogleshuohaizinib.cn
9、这个网站目前正常运行，据说还可在上面申请电子邮箱
www.abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxtzabcdefghijk.com
10、全部是数字6的域名
www.666666666666666666666666666666666666666666666666666666666666666.com
11、访问次数近70万的网站
www.3.141592653589793238462643383279502884197169399375105820974944592.com
3.5. Preferred name syntax
The DNS specifications attempt to be as general as possible in the rules
Mockapetris [Page 10]
RFC 1034 Domain Concepts and Facilities November 1987
for constructing domain names. The idea is that the name of any
existing object can be expressed as a domain name with minimal changes.
However, when assigning a domain name for an object, the prudent user
will select a name which satisfies both the rules of the domain system
and any existing rules for the object, whether these rules are published
or implied by existing programs.
For example, when naming a mail domain, the user should satisfy both the
rules of this memo and those in RFC-822. When creating a new host name,
the old rules for HOSTS.TXT should be followed. This avoids problems
when old software is converted to use domain names.
The following syntax will result in fewer problems with many
applications that use domain names (e.g., mail, TELNET).
::= | ” ”
::= | “.”
::= [ [ ] ]
::= |
::= | “-”
::= |
::= any one of the 52 alphabetic characters A through Z in
upper case and a through z in lower case
::= any one of the ten digits 0 through 9
Note that while upper and lower case letters are allowed in domain
names, no significance is attached to the case. That is, two names with
the same spelling but different case are to be treated as if identical.
The labels must follow the rules for ARPANET host names. They must
start with a letter, end with a letter or digit, and have as interior
characters only letters, digits, and hyphen. There are also some
restrictions on the length. Labels must be 63 characters or less.
For example, the following strings identify hosts in the Internet:
A.ISI.EDU XX.LCS.MIT.EDU SRI-NIC.ARPA
分类：Linux、操作系统、网络 | 标签： dns、linux |