Ping – How to Determine if a Machine is Online Without Using Ping

Okay, first - browser service is unrelated to icmp/ping. That service operates at a different level in the network stack. Most likely you are on the right track looking at the firewall configuration.

One of the "delightful" aspects of Windows 2008 is the firewall definitions have multiple dimensions. If you open up Windows Firewall with Advanced Security you can see protocols and ports on one tab (pretty obvious), scope on another one (also pretty obvious), but look at the advanced tab. There are profiles defined here. Now this is not inherently a problem except from time to time, especially after rebooting, Windows 2008 will "helpfully" Change Its Mind. So a profile selection that used to work fine will suddenly stop working - which could very well be what you are encountering here. I've ended up myself resorting to configuring my rules to always have "All profiles" selected on this tab and then rely only on the Scope tab to define allowed in/out ranges, etc.

Hope this helps. Good luck.

You can ping any IP address anywhere that network routing and firewalls allow, but that doesn't mean it's connected to your computer and so won't show up in netstat.

Netstat shows which TCP ports have got active connections (i.e. machines connected, not just machines which might or which used to connect). Ping uses ICMP (sometimes UDP) and doesn't rely on TCP ports.

In your case, it sounds like the application is not connecting but the operating system is still up and running, so you can ping the machine (because that's the OS responding), but the application can't connect to your server either because it's not running, or because it's got other issues.

If you can't connect back to it remotely and log in to check the app you'll need to send someone to it.

You also asked,

I have another question. If the outstation comes online but does not bind to the port 6102 will it not be shown in netstat? I think I know the answer here.

We don't know what OS or application this 'outstation' is running, but it's applications which connect to ports, and yet it's operating systems (or rather, components of those operating systems) which bring up and manage the network. So if you application connects, yes you'll see it. But if the outstation boots and brings up the network it won't do anything until the running application tries to do anything, if it crashes, then you'll see nothing at your end. Network and application are separate.

Last example, assuming your computer can connect to the internet, you can ping www.google.com but it doesn't mean www.google.com has ever tried to connect to your computer.