explicit DNS checks
The current monitoring seems to use resolvers with "hot" caches - hot means they are populated already by the periodic checks.
For many of ay checks this leads to a DNS resolution time of 0.
What would be good is a check which does the resolution from the start (root-servers) and implements the whole resolution process itself.
These kind of checks are resource intensive so they should be limited to every 5 minutes or so.
Additionally the whole dns resolution paths could be investigated like dnstrace by D.J. Bernstein does (dnstrace/dnstracesort are part of the tinydns package).
This doesn't fit really good into updown.io - maybe it would be good as a separate service.
Frank Tegtmeyer commented
Sorry - it's not the tinydns package but the djbdns package. Just to avoid confusion.