There are a number of ways to check this, however, we find the most reliable to be a simple whois check.
The tool we use most commonly is: https://whois.domaintools.com/
If your are using linux machine, you can follow up below given commands:
yum install whois // To install whois on linux system
whois domain.com // Replace domain.com with your domain name
Important: Some people will recommend you find the relevant nameservers of a domain via a DNS lookup, such as using whatsmydns.net – this is not correct. The reason we recommend the above method, is that this checks directly with the Registrar. DNS Zones are prone to errors, and can, therefore, reflect an incorrect value.