[Postfixbuch-users] PTR und CNAME zulässig?

Mathias Jeschke postfixbuch-users at gmj.cjb.net
Fr Okt 7 13:05:49 CEST 2011

Am 07.10.2011 12:57, schrieb Andreas Schulze:

>> laut RFC darf ein PTR record nicht auf einen CNAME verweisen.
> hast Du die konkrete Stelle zum nachlesen parat ?

Zitat (RFC 2181):

"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 of RFC1034 (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.

   Note that while the value of a PTR record must not be an alias, there
   is no requirement that the process of resolving a PTR record not
   encounter any aliases.  The label that is being looked up for a PTR
   value might have a CNAME record.  That is, it might be an alias.  The
   value of that CNAME RR, if not another alias, which it should not be,
   will give the location where the PTR record is found.  That record
   gives the result of the PTR type lookup.  This final result, the
   value of the PTR RR, is the label which must not be an alias."

Wobei "should not be" als DARF NICHT (IIRC) übersetzt wird.


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