[wp-hackers] New Codex page on WordPress Optimization

[Callum Macdonald]

Mail servers set their own queuing policies. For example, I've heard 
that Hotmail will only try once then bounce it back to the user.

I generally support the theory that distributed DNS is a good thing. 
Aside from anything else, it reduces the risk that DNS will go down and 
then who cares whether your servers are up?!

C.

Les Bessant wrote:
>> -----Original Message-----
>> From: wp-hackers-bounces at lists.automattic.com [mailto:wp-hackers-
>> bounces at lists.automattic.com] On Behalf Of Kimmo Suominen
>> Sent: 05 September 2007 07:21
>> To: wp-hackers at lists.automattic.com
>> Subject: Re: [wp-hackers] New Codex page on WordPress Optimization
>>
>>
>> On Tue, Sep 04, 2007 at 08:55:17PM +0100, Les Bessant wrote:
>>     
>>> Normal practice is to have at least two name servers, which should be
>>>       
>> on
>>     
>>> physically separate networks. If your name servers are on the same
>>>       
>> network
>>     
>>> as the application server, then in the event of a loss of
>>>       
>> connectivity, your
>>     
>>> domain drops off the internet in the worst possible way - rather than
>>> getting error messages indicating that the server is inaccessible,
>>>       
>> visitors
>>     
>>> will get "no such domain" errors.
>>>
>>> That's bad for web servers. If you're running email on the domain,
>>>       
>> it's
>>     
>>> potentially catastrophic - instead of messages being queued for
>>>       
>> delivery
>>     
>>> when the server comes back, they'll bounce with extreme force...
>>>       
>> That's not true.  You can only get "no such domain" if you get an
>> NXDOMAIN answer from a name server.  When none of the name servers can
>> be reached, you get a temporary failure (typically SERVFAIL or no
>> answer
>> at all).  Your website cannot be reached, but mail will be queued.
>>
>> If all your services are on a single network, it doesn't really buy
>> you much to have your name servers distributed outside it.  During an
>> outage, in the best case the visitor still gets a good DNS answer, but
>> won't be able to reach the site.  In the case of mail, the message
>> still
>> gets queued.
>>
>> Best regards,
>> + Kimmo
>>     
>
>
> That's interesting, but doesn't conform to my own experience of domains set
> up that way. I have seen mail bounce when the name servers for a domain are
> not contactable. With no MX records available, most mail servers I'm aware
> of will not queue mail but will return it to sender. Mail gets queued for
> redelivery attempts when the server knows where to send it - if there is no
> known destination it's less likely to be queued.
>
> Les
>
>
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