On 06/08/2023 13:01, Jon Smart wrote:
Hello,I know a hostname can point to multi-IPs. but can an IP have multi hostnames in PTR? 164.0.217.172.in-addr.arpa. 86400 IN PTR mia09s16-in-f4.1e100.net. 164.0.217.172.in-addr.arpa. 86400 IN PTR ord38s42-in-f4.1e100.net. 164.0.217.172.in-addr.arpa. 86400 IN PTR yyz08s10-in-f164.1e100.net. this IP does seem like so. I never know this.
RFC 2181 <https://www.rfc-editor.org/rfc/rfc2181#section-10.2> would seem to cover this:
10.2 <https://www.rfc-editor.org/rfc/rfc2181#section-10.2>. PTR records Confusion about canonical names has lead to a belief that a PTR record should have exactly one RR in its RRSet. This is incorrect, the relevant section ofRFC1034 <https://www.rfc-editor.org/rfc/rfc1034> (section 3.6.2 <https://www.rfc-editor.org/rfc/rfc2181#section-3.6.2>) indicates that the value of a PTR record should be a canonical name. That is, it should not be an alias. There is no implication in that section that only one PTR record is permitted for a name. No such restriction should be inferred.
Thanks.
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