LabSoft

function IPAdresToHost(const IP: string): string;
var
i: Integer;
p: PHostEnt;
begin
Result:=' ';
i:= inet_addr(PChar(IP));
if i <> u_long(INADDR_NONE) then
begin
p := GetHostByAddr(@i, SizeOf(Integer), PF_INET);
if p <> nil then Result := p^.h_name;
end
else
Result := 'Invalid IP address';
end;