How to achieve application reliability

James Smith jsmith at
Sun Dec 5 07:02:53 UTC 1999

With stuff like that you're still faced with a problem.  What if a
customer has been directed to a server that is working fine to begin with,
and then dies.  The 3DNS stuff will make the changes to avoid the server,
but the customer's browser won't pick up those DNS changes and they'll be
left hanging.  Also, you'd have to keep the DNS TTL low or else you have
to deal with the DNS info being caching on ISP server.  To further
complicate things the TTL is only the minimum required time to live.  I've
discovered instances where cached DNS information will be stored for
weeks, even though the authoritative DNS TTL was originally set to a day.
Our only alternative is to eliminate every single-point failure with stuff
like high availability clustering, redundant feeds, battery backups,
nuclear reactors, physical separate sites on different planets, etc. :-)
(Pardon me, it's 2:00am and I'm getting punching)

James Smith, CCNA
Network/System Administrator

2140 Winston Park Drive, Suite 203
Oakville, ON, CA L6H 5V5         
Tel:   905-829-3389 (email preferred)
Fax:  905-829-5692
1-877-DXSTORM (1-877-397-8676)

On Sat, 4 Dec 1999, Jason A. Mills wrote:

> Isn't this why you use things like F5/3DNS?
> Just curious...
> -Jason
> On Sun, 5 Dec 1999, James Smith wrote:
> > ...
> > internetsecure to type in the credit card.  The problem with Round-Robin
> > DNS is the possibility of the consumer's web browser picking up an IP
> > address of a server that is down.  If it was a real payment gateway, your
> > ...
> > 
> > --
> > James Smith, CCNA
>              Jason A. Mills            phyxis at
>     "We all live in a house on fire, no fire department to call, no way
> out, just the upstairs window to look out of while the fire burns the
> house down with us trapped, locked inside it." -- Tennessee Williams

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