Round Robin question

[Mark.Andrews at nominum.com]

	You don't need low ttls unless you are planning to update the
	rrset based on the availablity of the individual servers.

	Web clients should deal correctly with multi-homed sites and
	actually try multiple IP addresses if they can't get a answer
	from the first.  Multi-homed sites are common these days.  It
	is time to stop pandering to broken clients.

	Mark

> 
> Hi everyone,
> 
> I'm thinking of using  round robin DNS to act as my load
> balancer for my apache/jserv site.  Here's the basic
> situation:
> 
> In the past, I've only had to run one large
> webserver...there was stable traffic and the one server
> could handle the job.  Bursts of traffic are soon to be
> expected, and therefore, I'd like to do load balancing.
> Unfortunately, I don't have the money to buy fancy load
> balancing hardware.  So, I'd like to do accomplish this by
> using RR DNS.
> 
> I've never done this before and would like to ask a few
> questions:
> 
> a) I know I will have to play around with an appropriate
> ttl, but can anyone suggest something useful.   I've seen
> some sites with DNS lookup times as low as 5 seconds...this
> seems a bit ridiculous, but I guess is mainly dependent on
> need.  I estimate to have about 500K users per day coming to
> the site.
> 
> b) I'm a bit worried about bandwidth consumption.  It
> appears that running low ttl DNS on a highly requested site
> (500K users per day to the website) could really hammer the
> DNS servers and eat up bandwidth.  How can I calculate this
> bandwidth cost?
> 
> c) Are there any other issues I need to think about before
> implementing RR DNS?  Can anyone share their experiences?
> 
> Many thanks in advance,
> Thomas
> 
> 
> 
--
Mark Andrews, Nominum Inc.
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at nominum.com