Should DNS be on same server as webserver?
jalmberg at identry.com
Mon Jul 13 20:48:03 UTC 2009
On Jul 13, 2009, at 3:05 PM, Mel Flynn wrote:
> On Monday 13 July 2009 08:36:42 John Almberg wrote:
>> The other day, a FreeBSD 'expert' told me that it is important to
>> have the DNS server for a domain on the same server as the domain's
>> web server. Supposedly, this saves doing tons of DNS look ups over
>> the network. Instead, they are done locally.
> Bogus. A high-performance webserver should not be doing DNS
> lookups, other
> then application driven ones, like verification of email domains upon
> registration. If having hostnames in the live logs is mandatory by
> some weird
> company policy or the webserver does not provide a configuration
> setting to
> turn this behavior off, then more performance is gained by having the
> nameserver on the network gateway as the likeliness of cache hits and
> especially negative cache hits is increased. As others have
> mentioned, network
> overhead is negligible. Human noticeable delays are caused by
> upstream DNS
> servers slowly or not at all responding when a client IP is being
> Secondly, a named cache size depends on available memory. A high
> webserver uses plenty of that, so you wouldn't be able to grow the
> named cache
> to "almost caching the entire net" size, which you would be able to
> on a
> dedicated machine.
Thanks for all the comments on this topic. Glad I put 'expert' in
quotes. I had a feeling...
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