we have several servers colocated with several ISP's i am trying to sort out some configuration that would ensure good uptime for customers
i want to place the html documents of every customer on two separate servers connected to separate ISP's the dns servers will point to one server and the second one will be just a backup, in case the main server goes down we just change the DNS and point the affected domains to the backup server. when the main server is back up the dns changes back to normal and now my questions: 1. what should the times in zone files be set to to enable the dns change to be propagated very quickly, say 5 minutes max. is it possible/wise to use TTL=0 2. if a domain has 2 name servers set during registration, are both of these servers used for lookups? Or is it so that just the primary is querried if it works, and the secondary is querried only if the primary is not responding? 3. is this whole idea worth consideration anyway or should I forget it? thanks for answers Martin Dragun