Fail-over

[Pete Ehlke]

On Wed Feb 23, 2005 at 19:25:35 +0100, Eddy wrote:
>Norman Zhang wrote:
>> Hi,
>> 
>> I've a dual WAN router, currently some of my servers are bound with 
>> static IPs to ISP1. I like them to remain available on ISP2 if ISP1 goes 
>> down. Do I need dynDNS service for this? Or I can type in 2 different 
>> IPs for 1 serivce.
>> 
>> e.g.,
>> 
>> 1.2.3.4 IN www.example.com #ISP1
>> 2.3.4.5 IN www.example.com #ISP2.
>> 
>> But internet may still resolve to 1.2.3.4 despite ISP1 being down. May I 
>> ask what the best way to go about this?
>> 
>> Regards,
>> Norman Zhang
>> 
>> 
>If it is only for web access (like the example shown) you are lucky, 
>because modern browsers have the own built-in fail-over. Fail-over 
>during a session (https or statefull web application) might get you in 
>trouble, with this simple approach.
>
Thsi is completely 100% wrong. Internal browser caching of DNS
information makes the situion *worse*, not better. See
http://www.tenereillo.com/BrowserDNSCache.htm

-Pete