There a few approaches to take when monitoring DNS with Uptime Infrastructure Monitor: monitoring the process count, connecting to the port to ensure availability, and log monitoring to track any errors.

Process count

The Uptime Infrastructure Monitor Monitoring Station includes a Process Count Check monitor which, given a process name and threshold value, will collect the number of occurrences of the specified process. This service monitor requires that up.time Agent be installed on the target server.
Please review the online documentation for further details - Process Count Check

Port availability

The DNS service monitor issues a request similar to nslookup against the specified server and thresholds can be configured based on the response from the server.
Please review the online documentation for further details - Network Service Monitors

Log monitoring

Log monitoring is accomplished with a Plugin service monitor. Plugin service monitors are available on the Uptime Infrastructure Monitor Grid website and extend the out of the box functionality of up.time. Either the Enhanced Log File Monitor or UNIX Log Scanner plugin monitors would achieve this.