How do I programmatically check to see what domain I am connected to?

Question

If I'm connected to the local LAN here at work, I need to have my app access our server via an internal IP, otherwise, I'll need to use our external IP when out in the wild. Currently, I just try to connect via the local IP and then try the external if it fails... but the timeout takes a bit too long and I was wondering if there's a way to find out what domain the machine is connected to before trying. Edit: Patrick> Essentially, the app runs on a tablet pc that is connected to the local network a couple of times a day. It's roughly equal between the number of times it connects over the network and the times that it connects locally. All machines have a domain account when they are connected to the network (and have domain accounts with a naming convention of like "LOCTabletx" where x is a number given to the machine when it's ghosted. What I'm looking for is a fast way to see if the machine is connected on our local network or the internet. Using Environment.UserDomainName gets me LO…

Accepted Answer

Have you tried:

```
Environment.UserDomainName
```

You could also take a look at the active IP addresses on the machine, and query for one that works on your local network...

```
var x = NetworkInterface.GetAllNetworkInterfaces()
    .Where(ni => ni.OperationalStatus == OperationalStatus.Up)
    .SelectMany(ni => ni.GetIPProperties().UnicastAddresses);

// do something with the collection here to determine if you're on the right network.
// just looping & printing here for example.
foreach (var item in x)
{        
    Console.WriteLine(item.Address);
}
```

And after you've figured out the network that you're on, you could subscribe to the System.Net.NetworkInformation.NetworkChange.NetworkAddressChanged event to handle your computer jumping networks while your app is running.

How do I programmatically check to see what domain I am connected to?

Solution

Problem