Ultimate Pack  hot! Image Editor  new! Runtime Fusion Form Designer Object Inspector Print Suite Pro Commented Image Delphi Toys WinDowse Delphi Bonus TMS Scripter Studio Form Designer VB Form Designer .NET ...get more... for Delphi.NET, C#, VB.NET for Delphi VCL, BCB 3-6

	WinAPI Online Unix Manual Pages MegaDetailed.NET in3steps.com cdtrrracks.com new!   greatis.blogspot.com

Use IPAddrToName function. This function get host information by using GetHostByAddr function.

function IPAddrToName(IPAddr: string): string;
var
  SockAddrIn: TSockAddrIn;
  HostEnt: PHostEnt;
  WSAData: TWSAData;
begin
  WSAStartup($101, WSAData);
  SockAddrIn.sin_addr.s_addr:=inet_addr(PChar(IPAddr));
  HostEnt:= GetHostByAddr(@SockAddrIn.sin_addr.S_addr, 4, AF_INET);
  if HostEnt<>nil then
  begin
    Rresult:=StrPas(Hostent^.h_name)
  end
  else
  begin
    Result:='';
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  Label1.Caption:=IPAddrToName(Edit1.Text);
end;

For more

Win32 Programmer's reference

Download source