How not to make an error page (was: OT: www.Amazon.com down?)

Andy Litzinger Andy.Litzinger at theplatform.com
Fri Jun 6 13:49:42 CDT 2008


I've no idea what Amazon uses for Load Balancers, but I'm pretty sure
that error message is the default error message served up by a Netscaler
LB if no web services are available in the pool...

-andy

> -----Original Message-----
> From: Kevin Day [mailto:toasty at dragondata.com]
> Sent: Friday, June 06, 2008 11:40 AM
> To: Lasher, Donn
> Cc: nanog at nanog.org
> Subject: How not to make an error page (was: OT: www.Amazon.com down?)
> 
> 
> On Jun 6, 2008, at 1:24 PM, Lasher, Donn wrote:
> 
> > Checked, and doublechecked, not just me
> >
> > www.amazon.com returns:
> >
> > Http/1.1 Service Unavailable
> >
> > Anyone have a URL for a network/etc status page, or info on the
> > outage?
> > Been that way for a while this morning.
> >
> > -donn
> >
> >
> 
> Even worse, the page they're displaying is actually a HTTP 200
> response code(OK/no error), with no "Don't cache this" header - which
> means their error page is considered cacheable by some browsers/
> proxies. So, you may find users who tried to visit Amazon while they
> were down are still seeing it down long after they fix it.
> 
> Lesson to high profile websites: add these to your error pages so you
> don't have people complaining you're still down long after you're
> fixed.
> 
> * Don't return a 200 response code. Use 500 or 503. Nothing from 2xx
> or 4xx.
> * Add a "Cache-control: no-cache, must-revalidate, max-age=0" header,
> as well as an "Expires: 0" header for good measure.
> * If your server is really borked and you can't add headers at all,
> add '<META HTTP-EQUIV="Pragma" CONTENT="no-cache">' to the <head>
> section. That's not as good, but helps at least on the browser end.
> * If possible, add a timestamp to the page somewhere (even if it's in
> an HTML comment) so you can troubleshoot with users still seeing the
> error.
> 
> -- Kevin
> 





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