a beginner's questions on failover using DNS

[Rosie lee]

Dear all
 
I've just started investigating in this field and tried to find solutions for failover/load balacing using DNS (I also looked up some router solutions like those from Cisco which are far too expensive for SMEs). 
 
I checked the archives and found something related but quite a while ago. Hope somebody give  me any most recent information. 
 
In my case, a X company just got a broadband connection with much greater bandwith than the previous ADSL lines. And they want to use this as the primary network connection and keep the ADSL as backup options. Failover is the major concern here. So when the primary connection down, the ADSL can be used upon users' requests. I am not sure how Round Robin works when one of the servers fails (I am wondering if Round Robin just send a user an IP address on the top of the list no matter the host is down or not). 
Can RRset ordering option give a better solution currently? Are there any alternatives (like Microsoft DNS server) doing a better job than BIND?

Apart from the failover concern, it would be better if the spare ADSL could be used on a small traffic (eg, the ratio of primary IP to IP for ADSL is 80% : 20%). All the traffic will lead to backup ADSL only when is primary one is down. Concerning the SRV records, is it becoming a standard now?

Thanks in advance if anyone could give me some directions!

regards,

Rosie

 


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