PTR记录/反向DNS在网络托管中的所有用途是什么？

Question

PTR记录是否用于常见的web托管服务，如: smtp、pop、imap、dns解析、http、https、ftp、ssl和tls？

Answer 1

来自维基百科页面：

The most common uses of the reverse DNS include:

- The original use of the rDNS: network troubleshooting via tools such as
  traceroute, ping, and the "Received:" trace header field for SMTP e-mail,
  web sites tracking users (especially on Internet forums), etc.
- One e-mail anti-spam technique: checking the domain names in the rDNS to
  see if they are likely from dialup users, or dynamically assigned
  addresses unlikely to be used by legitimate mail servers. Owners of such
  IP addresses typically assign them generic rDNS names such as
  "1-2-3-4-dynamic-ip.example.com." Some anti-spam filters assume that
  email that originates from such addresses is likely to be spam, and may
  refuse connection.
- A forward-confirmed reverse DNS (FCrDNS) verification can create a form
  of authentication showing a valid relationship between the owner of a
  domain name and the owner of the server that has been given an IP
  address. While not very thorough, this validation is strong enough to
  often be used for whitelisting purposes, mainly because spammers and
  phishers usually can't pass verification for it when they use zombie
  computers to forge domains.
- System logging or monitoring tools often receive entries with the
  relevant devices specified only by IP addresses. To provide more
  human-usable data, these programs often perform a reverse lookup before
  writing the log, thus writing a name rather than the IP address.

Answer 2

用于查找PTR记录的常用方法是由垃圾邮件过滤器完成的。这个想法背后的概念是，在夜间发送电子邮件的垃圾邮件发送使用假域名一般不会有适当的反向PTR设置在ISP DNS区域。此标准用于垃圾邮件筛选器检测垃圾邮件。如果您的域没有适当的反向PTR记录设置，那么大多数电子邮件垃圾邮件过滤软件都会阻止您的邮件服务器发送电子邮件。