1) Is it so that GoDaddy accepts opalstack nameservers in USA ?
https://dcc.godaddy.com/manage/antarcticocean.dev
ns1.us.opalstack.com <-- San Francisco <-- OK
ns2.us.opalstack.com <-- New York <-- OK
ns3.us.opalstack.com <-- Texas <-- OK
whereas it did not accept
ns1.dk.opalstack.com <-- Frankfurt
ns1.sg.opalstack.com <-- Singapore
2) Are the following nameservers defined for Namecheap OK (it does accept them )?
https://ap.www.namecheap.com/domains/domaincontrolpanel/arcticocean.app
ns1.us.opalstack.com <-- San Francisco
ns2.us.opalstack.com <-- New York
ns1.dk.opalstack.com <-- Frankfurt
ns1.sg.opalstack.com <-- Singapore