Overview of Health Monitors
In addition to the inferences from passive monitoring, a pool may be configured with explicit Health Monitors that perform periodic tests and verify the correct operation of each node. By using health monitors, the Virtual Traffic Manager can detect failures even when no traffic is being handled.
The tests are performed at configured intervals against each node in a pool; if they fail sufficiently often, that node is marked as unavailable, and the Virtual Traffic Manager will stop sending traffic to that node. Pool-wide monitors just test a single machine and can be used to indicate that an entire pool is down.
A node that has been marked as having failed can be recovered only by the monitor that marked it as having failed.
The monitors are held in the Monitors Catalog and can be applied to any pool. Each performs a specific test. These range from simple tests, such as pinging each node, to more sophisticated tests which check that the appropriate port is open and the node is able to serve specified data, such as your home page.