NXDomain is a status of a domain that does not exist in the DNS zone. This means your nameservers are not returning DNS zone information for your domain. There can be many reasons why your domain shows this status, but the main reasons are: your domain is locked by the registrar (clientHold flag in whois), your DNS zone is not activated at your DNS host, your domain is expired, or there's a typo in your domain.
You first need to contact your DNS host and ask why your domain returns NXDomain.
If everything is fine with your DNS host, check your domain's whois, see if you have "clientHold" status, and contact your domain registrar.
If you are using private nameservers hosted by us, you may also want to check your domain's DNS zone. You can do that by clicking on Actions > Edit DNS Zone. If your DNS zone does not exist or there are errors, click on Actions > Reset DNS Zone. This action will rebuild your DNS zone, and hopefully, it will fix your issue as well.
