Are we still looking for other forms of life on this very planet? Are we sure now that DNA-based life and only of those four bases is the only form of life tha

Are we still looking for other forms of life on this very planet? Are we sure now that DNA-based life and only of those four bases is the only form of life that was born here? If "yes" then it means that it is highly probable that other forms of life are also DNA based, no?