Nameserver issues

One of my website hosts moved their servers, and in doing so, messed up the ns1/ns2 name servers for a number of domains.

When I tried to access the domain in New Zealand, the browser reported that the name server could not be found. But when I accessed the domain via a USA Proxy, I could see the domain.

While the whois reported the correct ns1/ns2, my isp xnet as well as xtras dns servers reported the old name server details.

I was able to see the reported nameservers via the following service.

http://dig.menandmice.com/knowledgehub/tools/dig

Name servers:
ns1.xnet.co.nz
alien.xtra.co.nz

The systems reported the old name servers.