Hybrid Cloud for Architects

ICMP monitoring 

This simply implies sending an ICMP echo packet, also known as network ping, and waiting for a response for a predefined period. The packet is stateless and can travel through a firewall. However, some firewalls decide to block it from a security standpoint, but ICMP is almost always available inside a data center. The packets don't take much to process (comparatively) and so don't cause much load on the server.

In the olden days, there was an attack where several thousand ICMP requests would flood the memory of the system, thereby disallowing credible requests and creating a denial of service attack. This kind of pinging was called the ping of death.  While most devices are immune to this attack, ICMP to this date is disallowed ...