Fail-over

[Eddy]

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.

Eddy