The Intelligent Service Verificator (ISV) service is the perfect complement to the Intelligent DNS (IDNS) module. In a context where multiple servers are performing the same task such as web servers, the ISV will monitor each of these servers to ensure that the traffic passed by the iDNS module is sent to a functioning server.
The ISV can perform two types of tests to verify a server or service’s availability, a Layer-7 (L7) exchange or a Layer-4 (L4) connection. The L4 tests will attempt to connect to the defined service on the specified TCP port and if the connection is successful the service is considered to be available. The L7 test will replicate a real user request for a web page (for example), gets the result from a web server and locates a keyword in the returned page to confirm that everything is in order.