f inhibition for ciprofloxacin could be considered sensitive for a given bacteria and a large zone around doxycycline could be considered insensitive?...

Can you explain to me how a smaller zone of inhibition for ciprofloxacin could be considered sensitive for a given bacteria and a large zone around doxycycline could be considered insensitive? I was told that this is possible and happens all the time. Can you please explain this to me? Thank you