When my DSL link got interrupted, last March, I had to go to a new upstream.
I paid the $29.95 per name server, to NSI, and got it straightened out in
less than four days. $30 bucks, for expedited service, isn't very expensive,
considering the alternative. All my domains are served by the same three
zone-servers, with backup zone-servers in AboveNet. After the main
zone-server were back online, I used the normal process to get the rest of
it straightened out, at no additional cost. That took a few extra weeks, but
once the main zone servers were online, I had no pressing time issues.