Make sure to remove the quotations on the NSLOOKUP.
In response, you should see a message that looks similar to this: The IP address that returns should match the IP address that is shown next to your hostname on the Hosts/Redirects page.
Does the IP address my hostname is resolving to match my current public IP address?
Login to your No-IP account and click Hosts/Redirects at the top left of the page.
If the IP address does not match the one listed by your hostname, you will need to manually update it to get your service working again.