static string GetLocalHostName () 
{ 
   string netBiosName = System.Environment.MachineName;
   //return netBiosName; 
 
   // Following method is deprecated 
   // string dnsName =  
   //   System.Net.Dns.GetHostByName("LocalHost").HostName; 
 
   string dnsName = System.Net.Dns.GetHostName();
   return dnsName;
}

Tips:
Avoid using pointers in unsafe code to access Windows data.