Make sure your PTR and A records match. For every IP address,there
should be a matching PTR record in the in-addr.arpa domain. If a
host is multi-homed,(more than one IP address) make sure that all IP
addresses have a corresponding PTR record (not just the first one).
Failure to have matching PTR and A records can cause loss of Internet
services similar to not being registered in the DNS at all. Also,
PTR records must point back to a valid A record,not a alias defined
by a CNAME. It is highly recommended that you use some software
which automates this checking,or generate your DNS data from a
database which automatically creates consistent data.
如果ISP保持每个PTR记录的A记录匹配,这对我没有任何意义吗？在我看来,如果PTR记录描述的IP地址托管对DNS不匹配的敏感服务(例如电子邮件托管),这一点非常重要.在这种情况下,前向区域将在域名下配置(示例遵循格式’zone – > record’)：
domain.tld – >邮件IN 1.2.3.4
并且PTR记录将配置为匹配：
3.2.1.in-addr.arpa – > 4 IN PTR mail.domain.tld.
是否有理由让ISP在其网络上主持正向查找IP地址？
ispdomain.tld – > broadband-ip-1 IN A 1.2.3.4
Would there be any reason for the ISP to host a forward lookup for an IP address on their network like this?
主要是一致性和完整性.虽然您可能很难想象为什么它很重要,但RFC的编写正是出于一个很好的理由：因此,互联网上的每个人都对其他人如何与他们进行互动有一致的基础理解.没有这个基础,互联网将是一个混乱的协议,无论任何人想要实现,没有任何期望的文档,兼容性,互操作性或一致性.
已知依赖于这些正向和反向查找的服务不应该是获得适当RFC处理的特殊服务.应该假设,如果你要和我们其他人一起参加,你将和我们其他人一样在同一级别的比赛场上比赛.
