Date: Mon, 13 Jul 2009 11:05:22 -0800 From: Mel Flynn <mel.flynn+fbsd.questions@mailing.thruhere.net> To: freebsd-questions@freebsd.org Subject: Re: Should DNS be on same server as webserver? Message-ID: <200907131105.22889.mel.flynn%2Bfbsd.questions@mailing.thruhere.net> In-Reply-To: <8195A2D9-F7AC-49F8-969E-A13EDFA3C05A@identry.com> References: <8195A2D9-F7AC-49F8-969E-A13EDFA3C05A@identry.com>
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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 resolved. Secondly, a named cache size depends on available memory. A high performance 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. -- Mel
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