有一个专用的DNS SPF记录,可用于SPF记录.但是,DNS TXT记录也可用于向后兼容.
如果我可以定义SPF记录 – 我应该删除已弃用的TXT记录还是留下它？
实际上在
RFC 7208,section 3.1.之后你应该只使用TXT类型记录：
SPF records MUST be published as a DNS TXT (type 16) Resource Record
(RR) [RFC1035] only. The character content of the record is encoded
as [US-ASCII]. Use of alternative DNS RR types was supported in
SPF’s experimental phase but has been discontinued.
SPFBR工作组已于2014年4月弃用SPF RR类型.对此的推理也可以在RFC 7208,section 3.1.中找到,其中淘汰了旧的RFC 4408：
In 2003,when SPF was first being developed,the requirements for assignment of a new DNS RR type were considerably more stringent than they are now. Additionally,support for easy deployment of new DNS RR types was not widely deployed in DNS servers and provisioning systems. As a result,developers of SPF found it easier and more practical to use the TXT RR type for SPF records.
