Below is a list of DNS Name Servers and IP addresses that can be used for your domains.
Plesk Linux Hosting / Resellers:
ns1.interlayer.net
ns2.interlayer.net
Plesk linux resellers can use any of the following IPs for private name servers:
173.254.250.124
173.254.250.125
Plesk - Windows Hosting / Resellers:
ns1.clientnshosting.net
ns2.clientnshosting.net
Plesk windows resellers can use the following IPs for private name servers:
173.254.250.120
173.254.250.121