Domain Name Server monitor

This poller checks the response time and health of a domain name server by polling it with an actual DNS query.
It can also be used to monitor the hostname resolution health of a single domain name. I might add the ability to test the A-record response from the server against an expected IP address.

URL format:

>dns://www.example.com[@8.8.8.8]

Domain name is required, the second parameter (IP address of DNS server) is optional and defaults to Google's public DNS server.