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Re: backup web server



On Mon, 28 Feb 2005, Kevin Coyner wrote:

> On Mon, Feb 28, 2005 at 05:03:05PM -0800, Alvin Oga wrote......
> 
> 
> > next best way ...  one server San Jose and one server in San Francisco
> 
> O.k.  Two boxes, each in a different physical location.
> 
> 
> > > Is it a combination of software and DNS?
> > 
> > MX for Mail ... ( webmaster@ ... ) for each
> > DNS is required ... each dns server uses itself to serve web pages
> 
> 
> I'm a bit mixed up here so let me walk through it.
> 
> domain name:  alwaysup.com
> 
> SanJose Box (ip 12.13.14.15)
> SFO     Box (ip 18.19.20.21)
> 
> Each runs DNS.  Each has an entry for alwaysup.com in its DNS config
> files.  Each has all the website files for alwaysup.com.
> 
> alwaysup.com has a typical domain name registrar, and the DNS entries at
> that registrar for alwaysup.com are 12.13.14.15 and 18.19.20.21 (our two
> boxes running DNS).

yup
 
> So now our website surfer in NY types in alwaysup.com into his/her browser.
> A typical DNS query for alwaysup.com would return 12.13.14.15, because
> that box is listed as primary DNS authority.

yup

>  But let's assume the SanJose box (12.13.14.15) is down, 

or too bz .. to reply this millisecond
or the other folks are downloading gazillion pics on the routers to SJ

> so it doesn't answer and the DNS
> request rolls down to SFO (18.19.20.21).  It answers that alwaysup.com
> is itself and serves up the page.
> 
> Is this right?

bingo  !! yup .. thats the idea

you will also want your DNS to be local to each box ...
	- always have DNS in your own pc .. nto at the registrar
	because you want to change to a new ip# in 5 seconds, not
	in 5 days

the trick is that yu need a "development" box to update new changes
into SFO or SJ ... and let it work for a day or week and than do the
same changes to the other box

you will also need to pull down your new database entries in
SFO/SJ boxes back inside ... ( it's good and bad to pull "insecure" data
from outside to inside, but on the other hand, you dont want your
outside browers to have access to inside DB either )

c ya
alvin



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