uses WinSock; 
 
var 
  HE: PHostEnt; 
  WSAD: TWSAData; 
 
function GetIP(HName: string): string; 
type 
  PAdr = array[0..249] of PInAddr; 
  PPAdr = ^PAdr; 
var 
  pp: PPAdr; 
  x: Integer; 
begin 
  Result := 'nicht gefunden'; 
  x := WSAStartup(MAKEWORD(2, 0), WSAD); 
  if x <> 0 then exit; 
  if copy(HName, 1, 7) = 'http://' then 
    HName := Copy(HName, 8, maxint) 
  else if copy(HName, 1, 2) = '\\' then 
    HName := Copy(HName, 3, maxint); 
  HE := GetHostByName(PChar(HName)); 
  if HE = nil then Exit; 
  Result := ''; 
  pp := PPAdr(HE^.h_addr_list); 
  for x := 0 to high(PAdr) do 
    if pp^[x] = nil then break 
    else Result := Result + inet_ntoa(pp^[x]^) + #13#10; 
  Result := Trim(Result); 
  WSACleanup; 
end; 
 
function IPToName(IPAddr: string): string; 
var 
  SAI: TSockAddrIn; 
  s1, s2, s3: string; 
  p: integer; 
begin 
  Result := 'nicht gefunden'; 
  try 
    p := pos('.', IPAddr); 
    s1 := inttostr(strtoint(copy(IPAddr, 1, p - 1))); 
    IPAddr := copy(IPAddr, p + 1, maxint); 
    p := pos('.', IPAddr); 
    s2 := inttostr(strtoint(copy(IPAddr, 1, p - 1))); 
    IPAddr := copy(IPAddr, p + 1, maxint); 
    p := pos('.', IPAddr); 
    s3 := inttostr(strtoint(copy(IPAddr, 1, p - 1))); 
    IPAddr := s1 + '.' + s2 + '.' + s3 + '.' + copy(IPAddr, p + 1, maxint); 
  except 
    exit; 
  end; 
  p := WSAStartup(MAKEWORD(2, 0), WSAD); 
  if p <> 0 then exit; 
  SAI.sin_addr.s_addr := inet_addr(PChar(IPAddr)); 
  HE := gethostbyaddr(@SAI.sin_addr.S_addr, 4, AF_INET); 
  if HE <> nil then 
    Result := string(HE^.h_name); 
  WSACleanup; 
end; 
 
// Beispielaufruf 
 
procedure TForm1.Button5Click(Sender: TObject); 
var 
  s: string; 
begin 
  s := GetIP('PC100'); 
  showmessage(s); 
  s := IPToName('002.227.007.036'); 
  showmessage(s); 
end;