Configuring different TTLs in multiple RRs for the same domain name, TYPE, and CLASS
ray at isc.org
Thu Mar 24 14:51:14 UTC 2016
On 24/03/2016 14:47, Ben Bridges wrote:
> Is it possible in BIND to configure multiple resource records for the
> same domain name, TYPE, and CLASS with different TTL values? For example:
> I tried it, and BIND set the TTL for all five records to 300 (or more
> specifically, the TTL of the first one of the RRs in the file). I
> looked for a BIND directive in the manual to change this behavior but
> could find no obvious candidate.
Doing so would be contrary to §5.2 of RFC 2181:
Resource Records also have a time to live (TTL). It is possible for
the RRs in an RRSet to have different TTLs. No uses for this have
been found that cannot be better accomplished in other ways. This
can, however, cause partial replies (not marked "truncated") from a
caching server, where the TTLs for some but not all the RRs in the
RRSet have expired.
Consequently the use of differing TTLs in an RRSet is hereby
deprecated, the TTLs of all RRs in an RRSet must be the same.
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