This is a case of his fast, DNS-based checking method not providing accurate results. You can see the difference by running nslookup and whois on the domain. Nslookup just uses DNS, whereas whois goes to the registrar/internic.

$ nslookup codejet.com

Server: 1.1.1.227 Address: 1.1.1.227#53

server can't find codejet.com: NXDOMAIN

$ whois codejet.com

Whois Server Version 2.0

Domain names in the .com and .net domains can now be registered with many different competing registrars. Go to http://www.internic.net for detailed information.

   Domain Name: CODEJET.COM
   Registrar: GODADDY.COM, LLC
   Whois Server: whois.godaddy.com
   Referral URL: http://registrar.godaddy.com
   Name Server: No nameserver
   Status: clientDeleteProhibited
   Status: clientRenewProhibited
   Status: clientTransferProhibited
   Status: clientUpdateProhibited
   Updated Date: 20-may-2011
   Creation Date: 01-jun-2000
   Expiration Date: 01-jun-2012

>>> Last update of whois database: Mon, 16 Jan 2012 19:34:42 UTC <<<