Macbook Pro OSX 10.10.5, Late 2013 model. Firewall entirely off (Stealth mode is certainly off). Three Macbook Pro’s wirelessly connected to the same wireless network (WPA/WPA2 Personal) under the same netmask with one and only wireless router (192.168.0.1).
Mac 1: inet 192.168.0.101 netmask 0xffffff00 broadcast 192.168.0.255 Mac 2: inet 192.168.0.105 netmask 0xffffff00 broadcast 192.168.0.255 Mac 3: inet 192.168.0.119 netmask 0xffffff00 broadcast 192.168.0.255
If ping each other, one will receive a permanent Request timeout for icmp_seq. If ping a random non-exist address (192.168.0.188), I get No route to host after Request timeout for icmp_seq. If any OS X ping the router (192.168.0.1), then it gets all packets transmitted and received with 0.0% loss.
From the results I assume the OS X can ping router and the router tries to transmit the packet if the IP exist,