Date: Tue, 14 Nov 1995 10:28:06 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: jgreco@brasil.moneng.mei.com (Joe Greco) Cc: terry@lambert.org, luigi@labinfo.iet.unipi.it, hackers@FreeBSD.org Subject: Re: Multiple http servers - howto ? Message-ID: <199511141728.KAA20264@phaeton.artisoft.com> In-Reply-To: <199511141700.LAA28800@brasil.moneng.mei.com> from "Joe Greco" at Nov 14, 95 11:00:19 am
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> > #1. Via DNS. The requesting hosts are rotored through a list of the > > addresses. > > > > It isn't a very good scheme, mostly because caching exists. > > Which is why you lower the TTL :-) or maybe just not worry about it, > because when you start examining the Bigger Picture, you realize that a site > large enough to require multiple servers is receiving zillions of requests, > and different data will be cached by each domain server, still effectively > spreading the load over multiple servers. *My* cache doesn't have to honor *your* TTL. In fact, if my provider is Sprint or one of serval others, it *won't* honor your TTL. You're still doing round-robin address assignment, which expects that clients will behave statistically identical to one another. And they won't, even if the TTL is honored. > The case where you might lose is if a hundred workstations at the same site > suddenly decide to all run Netscape on a particular URL at once, all hundred > workstations receive the same cached answer from the local domain server, > and they proceed to pound the box into oblivion. This is the "University > Intro to CS class" problem. It's worse if they are pounding on your news > server :-( which HAS happened to me. Or one of several server boxes with 40 X terminals hanging off it. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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