From: blodwick (blodwick@columbus.rr.com)
Date: Tue Nov 29 2005 - 10:51:25 GMT-3
I believe what Leigh is talking about is an intelligent DNS device that
communicates state information either directly with the server or with a
local content device before sending resolution. The Cisco device is
called a Global Site Selector (GSS). If you were to use DNS round robin
you would obviously be sent to a non-working server 50% of the time
during an outage (if you had 2 data center options). There are further
advantages if you use the Cisco Content Services Switch (CSS) locally at
each data center and use the GSS to control disaster recovery. The CSS
locally at each data center can load-balance the local servers and will
communicate to the GSS local state information. With the CSS locally you
can also utilize scripted keepalives to take establishing server "state"
to the next level. This subject gets quite involved, but imagine being
able to query a java applet on your web server that would in turn query
your back end database. You would be able to assure that users were
always being sent to a web server that has an operational web engine,
know java is operating properly and that your backend database is
reachable and responding properly to queries.
~ Brian L
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Ian Stong
Sent: Tuesday, November 29, 2005 8:10 AM
To: 'Leigh Harrison'; 'FORUM'
Subject: RE: DNS Disaster Recovery Question
Haven't worked with them myself. Curious what else they provide since
just
setting the TTL to 5 mins can be done by anyone. It's just a setting
you
use on the NS entries of your DNS server. You could even use a free DNS
hosting service such as zoneedit.com and set your TTL to 5 mins.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Leigh Harrison
Sent: Tuesday, November 29, 2005 6:04 AM
To: FORUM
Subject: DNS Disaster Recovery Question
All,
A customer of mine has asked me to look at a company called
Netnames.com.
This is to do with using DNS for disaster recovery, i.e., changing the
ip address to point at a server in a different data centre.
Their solution is to change the TTL on the customers DNS to 5 mins, you
can also log in to change it if need be.
Have any of you service provider chaps come across this place? Is there
an alternative/easier/cheaper solution?
Any comments/suggestions greatly welcomed.
LH
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