[ccnpding]

thanks mariol.
1. actually the ISP's DNS server now works as secondary DNS server for me, and the primary DNS server sits behind my FW.
then how can the secondary DNS(ISP's DNS server) know that one of my ISP link is down and replies to client request with the IP reachable instead of the one unreachable?

2. i learn that this can be done with Link Selection which can be done in R60 and later ver.
but how can Link selection be done in R55 secureplatform?

the question is really interesting, and i'm planning to implement ISP redundancy and VPN redundancy here.