Internet Assigned Number Authority (IANA) provides a web version to check if your DNS name servers are not recursive. Visit http://recursive.iana.org/ to check your website name server. All you need to do is submit your domain for the system to analyze it. For example, king.net then click Submit Query.

You should see a similar results, as depicted below.
Safe.
The servers tested for KING.NET are not vulnerable to cache poisoning.

Name server - IP Address - Results
DNS1.NAME-SERVICES.COM - 69.25.142.42 - Not recursive
DNS2.NAME-SERVICES.COM - 216.52.184.248 - Not recursive
DNS3.NAME-SERVICES.COM - 63.251.92.200 - Not recursive
DNS4.NAME-SERVICES.COM - 69.64.145.225 - Not recursive
DNS5.NAME-SERVICES.COM - 70.42.37.7 - Not recursive

Disclaimer about the tool:
Notes about this tool
This tool has been implemented quickly to assist name server operators. It may have problems as it has not been thoroughly tested, so you should also perform your own tests and use this only as a guide. We appreciate any comments or bug reports on this tool — please drop a note to iana@iana.org. Port entropy results provided by DNS-OARC.