By using the Response Time you can verify the response times from the check agent to the DNS Server.
Check Info
...
Check Result
...
Usage
The Response Time check queries the defined name server or a default resolver five times in a row and calculates the average response time for the calls.
The check can use a specified query (A Record, AAAA, CNAME, or SOA) in the request, or be allowed to select automatically.
Alerts
The check will also keep track of timeouts and create test results based on the number of occurrences.
...