完全合格的域名是否需要句点？
Does a Fully Qualified Domain Name need a period?
我对 FQDN（完全限定域名）感到困惑。 FQDN 是否需要以句号结尾？喜欢 sun 或 sun.tuc.noao.edu. 或 sun.tuc.noao.edu。有什么区别？
How IT Works: Domain Name
System
All DNS records actually end with the period character (.) which
represents the root of the DNS hierarchy, but it's rarely printed and
is usually just assumed. A domain name that includes the trailing
period character is said to be a Fully Qualified Domain Name (FQDN).
However, domain names where the period character is implicit are also
commonly referred to as FQDNs.
Source: TechNet Magazine
另请参阅：
通常你不会（点）。在 FQDN 的末尾，除非它在 DNS 中。
如果您在大多数情况下为内部 machine/server 添加此 FQDN，我们不会在末尾添加（点）。
看看 [2] DNS 规范，RFC 1034，早在 1987 年：
When a user needs to type a domain name, the length of each label is
omitted and the labels are separated by dots ("."). Since a complete
domain name ends with the root label, this leads to a printed form
which ends in a dot. We use this property to distinguish between:
a character string which represents a complete domain name
(often called "absolute"). For example, "poneria.ISI.EDU."
a character string that represents the starting labels of a
domain name which is incomplete, and should be completed by
local software using knowledge of the local domain (often
called "relative"). For example, "poneria" used in the
ISI.EDU domain.
参考文献：
我对 FQDN（完全限定域名）感到困惑。 FQDN 是否需要以句号结尾？喜欢 sun 或 sun.tuc.noao.edu. 或 sun.tuc.noao.edu。有什么区别？
How IT Works: Domain Name System
All DNS records actually end with the period character (.) which represents the root of the DNS hierarchy, but it's rarely printed and is usually just assumed. A domain name that includes the trailing period character is said to be a Fully Qualified Domain Name (FQDN). However, domain names where the period character is implicit are also commonly referred to as FQDNs.
Source: TechNet Magazine
另请参阅：
通常你不会（点）。在 FQDN 的末尾，除非它在 DNS 中。 如果您在大多数情况下为内部 machine/server 添加此 FQDN，我们不会在末尾添加（点）。
看看 [2] DNS 规范，RFC 1034，早在 1987 年：
When a user needs to type a domain name, the length of each label is omitted and the labels are separated by dots ("."). Since a complete domain name ends with the root label, this leads to a printed form which ends in a dot. We use this property to distinguish between:
a character string which represents a complete domain name (often called "absolute"). For example, "poneria.ISI.EDU."
a character string that represents the starting labels of a domain name which is incomplete, and should be completed by local software using knowledge of the local domain (often called "relative"). For example, "poneria" used in the ISI.EDU domain.
参考文献：