[wp-hackers] New Codex page on WordPress Optimization
kimmo at global-wire.fi
Wed Sep 5 06:21:28 GMT 2007
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
<A HREF="http://kimmo.suominen.com/">Kimmo Suominen</A>
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