It is simple to check your domain registration details.
If the domain is a a .uk .co.uk .org.uk .me.uk .cymru or .wales then you can use Nominet's Whois tool:- http://www.nominet.uk/whois/
If the domain is non of the above we recommend using: http://whois.domaintools.com/
This information will also show you the Registrar and the Hosting Nameservers.