we are encountering a very strange phenomenon. We can ping a specific windows server in one of our data centres from any other random server in any of our data centres across the world except from ONE single host among over 600 servers. Even with firewall down, the linux box cannot ping the windows server, but it can traceroute. Furthermore, it can also ping -R (!) , just not ping on its own. Ping from all other linux hosts to that windows machine works perfectly well.