resolver: incorrect TTL used with A+CNAME response

[Sergey Kandaurov]

By default, nginx caches responses using the TTL value of a response.

The resolver doesn't fully operate correctly on multiple entries
received together in one DNS response.
For example, when the received answer contains multiple records as follows:
upstream 60 CNAME cname1
cname1 86400 A 10.10.10.10

Here the CNAME resolution stage would be "skipped", and the resolver cache
will store for "upstream" a finally resolved address with TTL 86400.

References: ​http://mailman.nginx.org/pipermail/nginx-ru/2013-April/050744.html

[maxim]

The original reporter created ticket #331, already closed as a duplicate.

[Ruslan Ermilov <ru@…>]

In 8958656a8060ff395b3f1a417266ebf261136625/nginx:

Resolver: use minimum TTL for caching (ticket #329).