Isolexis Monitor monitors Internet based services such as web, FTP, DNS, TCP, UDP, TFTP, SNMP, and disk space. It allows for alerting by sound, email, pager, and syslog message. It keeps track of probes by writing to files, web pages, CSV files, HTML and XML files. Isolexis Monitor allows you to monitor multiple services running on the Internet. It allows a webmaster to make sure that the web sites are constantly running. It allows a system administrator to probe any TCP port to make sure that critical services such as the Domain Name Service (DNS), Mail servers, TFTP, and Web servers are responding. Additionally it allows monitoring of URLs to make sure that they contain certain text or that the size returned exceeds some lower or upper bound. For FTP services Isolexis Monitor allows checking for the existence of a file as well to make sure that the size of the file is appropriate. Checking of SNMP system up time is also supported so that SNMP enabled devices can be monitored. Disk space monitoring on local hard drives and mounted shared is also supported with the ability to set a low disk space threshold. Included is a fast port scanner for determining the TCP ports on which a server is listening.