Zones and RSCN

Hello,

I'm new to SANs so please excuse my ignorance. I've been reading
about zoning and RSCNs. From what I've read RSCNs are sent to all
members of a zone after a change in the port status occurs on a port
in that zone. For example, if all servers are in the same zone, and
one of them is rebooted, an RSCN is sent to all the other hosts in
that same zone to notify them of the event. At this time are the
other hosts in the zone "knocked offline" termporarily while they do
name server refresh? How can you prevent this? I've read a post that
somebody said to create one zone per port, this way it won't affect
any other hosts. What can you do if you have a backup type
environment where all hosts need to speak to one host (the backup
server)?

-TIA