supposed you needed to modify the dns information across all your existing domains. let’s say you want to add a nameserver that’ll be used by all your domains, you can do this:
for i in `cat /tmp/domains`;do ./dns -a $i -ns “” -nameserver ns100.domain.com;done
/tmp/domains – list of your domains
ns100.domain.com – dns server to be added
the “./dns” part refers to a php script located in plesk’s install folder, you can use it to modify dns entries for your domain/s.