How to resolve hostname from local IP in C#.NET?

Question

I'm trying to list the names of the computer names currently online on a network. I've only managed to get the get active IPs but I cannot get the computer name of these IPs. Any ideas ?

Answer 1

You can use Dns.GetHostEntry to try to resolve the name, because not every IP has a name.

using System.Net;
...

public string GetHostName(string ipAddress)
{
    try
    {
        IPHostEntry entry = Dns.GetHostEntry(ipAddress);
        if (entry != null)
        {
           return entry.HostName;
        }
    }
    catch (SocketException ex)
    {
       //unknown host or
       //not every IP has a name
       //log exception (manage it)
    }

    return null;
}

Answer 2

If you've already got a list of ip adresses, you can find the name with:

      System.Net.Dns.GetHostEntry("youripaddress").HostName;