SNIPS (System & Network Integrated Polling Software), formally NOCOL, is a system and network monitoring software that runs on Unix systems and can monitor network and system devices. It is capable of monitoring DNS, NTP, TCP or web ports, host performance, syslogs, radius servers, BGP peers, etc. New monitors can be added easily (via a C or Perl API).
False alarms are avoided by escalating events through severity levels- hence if a site is unreachable, the site will be tested multiple times before finally indicating that it is 'critical'. All events are logged, and the operator has the capability to decide which level to view the events at.