Also, DNS cacheing on the client will get in the way of this. I have an
app that sends e-mails via a pool
of SMTP servers.  When it can't contact the chosen server, the app has to
flush the DNS cache before
trying to send again.



Chuck Tribolet
[email protected] (IBM business)
[email protected] (Personal)
http://www.almaden.ibm.com/cs/people/triblet

Linux on 390 Port <[email protected]> wrote on 06/10/2011 02:08:37
PM:

> From: Alan Altmark/Endicott/IBM@IBMUS
> To: [email protected]
> Date: 06/10/2011 02:13 PM
> Subject: Re: Networking Question
> Sent by: Linux on 390 Port <[email protected]>
>
> On Friday, 06/10/2011 at 04:23 EDT, Lionel Dyck/Oakland/IBM@IBMUS wrote:
>
> > Is there a way to setup the DNS so that both host ip addresses are
> defined
> > for a single hostname?
>
> Yes [see Rick's post], but that likely isn't going to do what you want.
> Most end-user client applications are simplistic, simply using the first
> IP address returned by the DNS server.  The DNS server may order the IP
> addresses differently each time resolution is performed (round robin),
but
> you can't really depend on it since it depends on the specific DNS
server
> implementation.
>
> More sophisticated clients (often found in server-class clients such as
> SMTP) will use the entire list of IP addresses and try each in sequence
> until the connection succeeds or the list is exhausted.
>
> Alan Altmark
>
> z/VM and Linux on System z Consultant
> IBM System Lab Services and Training
> ibm.com/systems/services/labservices
> office: 607.429.3323
> mobile; 607.321.7556
> [email protected]
> IBM Endicott
>
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