Concepts

After discovering all hosts in your network, nVision scans for services running on them. It scans only a sub range of all available services. To read how to select services to be scanned, refer to Program Options topic.

Service scanner not only checks if a service port is open. It also sends a specific request and checks if a response matches predefined criteria. If so, the service is being added to the host and nVision starts to monitor it.

The service monitor uses a similar mechanism as the service scanner: it sends specific requests to the TCP/UDP port (service) and logs the response time and percent of requests (packets) lost. It also checks if the received response matches specific criteria.

You can also monitor several types of counters with nVision. The table below lists available counters:

Counter type	Description
Host status	Indicates host status for every minute. Allows reporting of hosts availability.
SNMP	SNMP counters are provided by SNMP protocol available on routers and most servers. They allow the information such as network transfer, number of users, CPU utilization, etc. to be monitored.
Windows	nVision can monitor all Windows counters including those provided by non-system applications like MS SQL Server or Ex-change Server.
Page load time	Measures the loading time of a specific web page.
Page content change	Indicates selected web page changes.
POP3 login time	Checks the time to login to the POP3 server.
SMTP send time	Measures the time required to send an e-mail.

Unlike in other similar products, host status in nVision is a calculated value, not a hard coded one. So you can define conditions when a host is considered to have status <Up>, <Down> and <Warning>. For more information about host status refer to Host status concept topic.