On 09/21/2010 12:07 AM, Curtis wrote:
In the case where transport_maps is used to designate the next hop
destination of a message like this:
customer.domain smtp:[mail.customer.domain]
...and the customer uses round robin dns for mail.customer.domain so
that it points to multiple IPs like this:
mail.customer.domain. 900 IN A 111.111.111.111
mail.customer.domain. 900 IN A 222.222.222.222
mail.customer.domain. 900 IN A 333.333.333.333
....will postfix rotate between the ips that it delivers to?
Yes.
Or, will it cache the first IP (111.111.111.111) and just deliver to
that host until the next time postfix is reloaded
No.
or the local DNS cache for the for mail.customer.domain expires?
Yes.
Also consider that that is not how a DNS cache works.
On the first query for that A record, all results are returned by an
origin server, and cached.
Postfix, too, gets all results from the cache.
Assume that postfix will abide by any relevant RFCs for DNS.
--
J.
