2019独角兽企业重金招聘Python工程师标准>>> 
域名后加个点是什么意思比如用www.baidu.com.访问也可以
http://stackoverflow.com/questions/19480767/domain-names-with-dots-at-the-end
怎么查看**权威**的域名解析信息,默认出来都是Non-authoritative answer
http://stackoverflow.com/questions/38021/how-do-i-find-the-authoritative-name-server-for-a-domain-name?rq=1
什么是CNAME什么是canonical name?
英文释义: http://www.techopedia.com/definition/1321/canonical-name-cname
`Definition - What does Canonical Name (CNAME) mean?`
Canonical name (CNAME) is a record in the DNS database that indicates the true host name of a computer associated with its aliases. It is essential when running multiple services from a single IP address.
`Techopedia explains Canonical Name (CNAME)`
A canonical name (CNAME) is a properly denoted host name of computers or a network server. **CNAMEs specify an alias or nickname for the canonical host name record in domain name systems**.
CNAME records are generally defined in RFC 1034. The records within CNAME are handled in the domain name system and have restrictions on their usage. When a domain name system finds a CNAME record while searching for a regular resource record, it restarts the query using the canonical name. The canonical name that a CNAME record points to lies anywhere in the domain name system, even if it is a local or remote server in a different DNS zone. CNAME often refers to the label or left-hand part of a CNAME record.
**简而言之, CNAME是canonical name的别名.**
一个规范名（canonical name）是一台计算机或网络服务器的完全标识主机名。在域名服务系统(DNS)数据库中一个CNAME为一个规范主机名记录指定一个别名或昵称。在编程时，“规范”一词的意思就是“根据规则”。DNS是在因特网中定义站点（特别是Web站点）地址的标准方法。