[wp-hackers] New Codex page on WordPress Optimization
lists.automattic.com at callum-macdonald.com
Wed Sep 5 08:23:52 GMT 2007
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?!
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
>>> physically separate networks. If your name servers are on the same
>>> 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,
>>> will get "no such domain" errors.
>>> That's bad for web servers. If you're running email on the domain,
>>> potentially catastrophic - instead of messages being queued for
>>> 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
>> 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
>> 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.
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