Created on 2005-07-14 by Rainer Gerhards.
ALiveMon's ping monitor checks that a remote system is operational.
With ping, AliveMon sends a special request (called
an ICMP echo request) to the
remote system (the one to be monitored). The remote system acknowledges the
receiption of that request back to AliveMon (called an ICMP echo reply). When
that acknowledgment is received by AliveMon, it knows that the remote system is
powered up, connected to the network, the operating system is loaded and its IP
protocol act correctly.
This all is good indication that the machine is
online. It does not, however, mean that all services on that machine are
actually alive. For example, the mail server might have stopped for some reason
(as simple as disk space shortage). So ping can NOT tell you if all services
on the remote machine are OK. To check this, you must specifically monitor
these services, which can be done with AliveMon's application-level monitoring
capabilities. Application-level monitoring works with allmost all TCP-based
applications as well as with some UDP services (for example,
popular game servers are supported).
You can define your own application-level monitors if you know the protocol
specifics (or ask our support folks to
help you out with it).
If you are evaluating uptime monitoring tools, make
sure that the tool in question supports application-level monitoring. With
just a ping-based approach, you can not be 100% sure all is well. For the same
reason, it pays to check system health not only via ping monitors, but via
application-specific ones. Fortunately, AliveMon can create them by default
during automatted network discovery.