DNS/1/資源レコード/DNAME/Acceptanceについて、ここに記述してください。


キャッシュにあるレコードと返答(DNAME入)とが相容れない場合が生じることがある。

その時の処理方法が説明されていて、これは毒盛防止の原則に通じるものがある。-- ToshinoriMaeno <<DateTime(2019-09-05T22:57:51+0900)>>

{{{

3.4.  Acceptance and Intermediate Storage

   Recursive caching name servers can encounter data at names below the
   owner name of a DNAME RR, due to a change at the authoritative server
   where data from before and after the change resides in the cache.

   This conflict situation is a transitional phase that ends when the
   old data times out.  The caching name server can opt to store both
   old and new data and treat each as if the other did not exist, or
   drop the old data, or drop the longer domain name.  In any approach,
   consistency returns after the older data TTL times out.

   Recursive caching name servers MUST perform CNAME synthesis on behalf
   of clients.

   If a recursive caching name server encounters a DNSSEC validated
   DNAME RR that contradicts information already in the cache (excluding
   CNAME records), it SHOULD cache the DNAME RR, but it MAY cache the
   CNAME record received along with it, subject to the rules for CNAME.
   If the DNAME RR cannot be validated via DNSSEC (i.e., not BOGUS, but
   not able to validate), the recursive caching server SHOULD NOT cache
   the DNAME RR but MAY cache the CNAME record received along with it,
   subject to the rules for CNAME.

}}}