cStatus is a free app that has two main functions: to monitor and to scan a network.

Features:

A monitoring system with:
ICMP ping monitoring
TCP port monitoring (TCP ping)
Statistical information
Charting
Simple alarm system
Allows opening a host with several tools: RDP, HTTP, FTP, etc.
Host display filtering system

An IP scanner:
MAC information and MAC vendor detection
Hostname retrieval with the possibility to change DNS query server
Port scanner
Allows adding to the monitoring, one of the IPs that has been detected
Host display filtering system

A graphical Trace Route:
Shows the route (hops) through the network between your computer and a specified destination computer.
Calculates and displays the amount of time each hop took
Hostname retrieval with the possibility to change DNS query server
Allows adding to the monitoring one of the IPs that has been detected