On Tue, 22 Oct 2019 08:59:17 +0200 Ingeborg Hellemo ingeborg.hellemo@uit.no wrote:

The NAV service monitor lets you monitor DNS. You then get graphs for availability and response time.

Does this measure UDP or TCP response time?

Excellent question, Ingeborg.

The availability and response data is collected by the servicemon engine on a generic basis, so what it *actually* measures is the time spent in each service checker plugin instance (which means "response" time depends entirely on what the plugin in question is actually doing), and the availability is based on whether the plugin run resulted in an OK/NOT OK result.

Apparently, the DnsChecker plugin only supports UDP, and does not support fallback to TCP when the request or response becomes too large (meaning: A too large response will therefore result in a "dns service is down" event in NAV).