子域中允许使用哪些字符? [英] What are the allowed characters in a subdomain?

问题描述

您可以在子域中使用哪些字符?

What characters are you allowed to use in a subdomain?

示例:对于 someSub.example.com，someSub 部分.

Example: for someSub.example.com the someSub portion.

我知道您可以使用字母、数字和连字符，但其他字符呢?可以使用_(下划线)吗?

I know you can use letters, numbers, and hyphens, but what about other characters? Can _ (underscore) be used?

推荐答案

字母(重读 à 除外)、数字 0-9 和连字符.

Letters (except stressed à), Numbers 0-9 and Hyphen.

http://en.wikipedia.org/wiki/Domain_name摘抄:可以在域名中使用的有效字符是:

http://en.wikipedia.org/wiki/Domain_name excerpt: Valid characters that can be used in a domain name are:

a-z
0-9
- but not as a starting or ending character
. as a separator for the textual portions of a domain name

来自 http://tools.ietf.org/html/rfc1035

DNS 中的各种对象和参数都有大小限制.他们是下面列出.有些可以很容易地改变，有些则更基础.

Various objects and parameters in the DNS have size limits. They are listed below. Some could be easily changed, others are more fundamental.

labels          63 octets or less
names           255 octets or less
TTL             positive values of a signed 32 bit number.
UDP messages    512 octets or less

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