Re: Will browsers support multiple proxy servers?

Daniel O'Callaghan wrote:
# On Tue, 20 Jun 1995, Monica Berko wrote:
# > We do not have a firewall but run a proxy/caching server to improve
# > performance and save network traffic costs.
# > 
# > However it is a single point of failure because we don't have an automatic
# > failover strategy and no out-of-hours coverage. What I would like is to be
# > able to configure the browsers with at least two proxy servers (one as the
# > default) just as one does with DNS nameservers, and run a proxy server
# > (without cache) on another system just in case the main server fails.
# Monica,
# It will be a while before browsers can do this.  I suggest you organise a 
# specific machine ready to take over proxying, and implement commented out 
# lines in your DNS files so the pointer to wwwproxy.anu.edu.au can be 
# switched easily.  Alternatively, have a separate machine which you can easily
# re-ifconfig to the appropriate IP address. Or, really getting fancy,
# put the two machines on different nets (same IP address) and control who 
# gets the traffic by changing a static route in the rotuer.

I agree that it will be a while before clients will be able to implement
this.  That is why we have come up with an alternative solution by means
of DNS 'trickery' to have a 'secondary' Web server in case the 'primary'
one fails.  Therefore, you don't have to rely on the clients, which you
have no control over, but the servers, which you do.

Here is what we have done for www.wdc.com (Western Digital):
	www is actually a sub-domain with two NS records -- one is
	the main server, the other the backup ( I will not use the terms
	primary and secondary to avoid confusion with DNS terminology)

	BOTH servers are then declared to be primary for that domain

	NEITHER of them contain info about the other server, but ONLY
	contain records for themselves

	BOTH are configured with very low cache timeout values so that 
	in case of a server failure, clients will not resolve the 'wrong' 

	Therefore, when clients try to resolve www.wdc.com, USUALLY the 
	main server responds.  But in case it doesn't (in the event of a
	possible server crash, or more often, in case of DNS timeout
	between clients and the main server), then the backup responds.

Sorry if that was confusing -- I think it will be more clear if you just
go ahead and check out the DNS records yourself.

# Danny

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