ArgumentNullException system.net.dns exampple
public static IPHostEntry GetHostEntry(string hostNameOrAddress) {
if(Logging.On)Logging.Enter(Logging.Sockets, "DNS", "GetHostEntry", hostNameOrAddress);
//
// demand Unrestricted DnsPermission for this call
//
s_DnsPermission.Demand();
if (hostNameOrAddress == null) {
throw new ArgumentNullException("hostNameOrAddress");
}
// See if it's an IP Address.
IPAddress address;
IPHostEntry ipHostEntry;
if (IPAddress.TryParse(hostNameOrAddress, out address))
{
if (address.Equals(IPAddress.Any) || address.Equals(IPAddress.IPv6Any))
{
throw new ArgumentException(SR.GetString(SR.net_invalid_ip_addr), "hostNameOrAddress");
}
ipHostEntry = InternalGetHostByAddress(address, true);
}
else
{
ipHostEntry = InternalGetHostByName(hostNameOrAddress, true);
}
if (Logging.On) Logging.Exit(Logging.Sockets, "DNS", "GetHostEntry", ipHostEntry);
return ipHostEntry;
}