My syrup goes in a pail (bucket) feeder inside the hive, like this:
I would never leave syrup open outside the hive - too much risk of attracting robbers (bees from other colonies), wasps, ants and other pests. I don’t even like entrance feeders, because likewise they tend to increase robbing behavior in my experience. The pail feeder inside the hive is effective and carries none of the above risks, as long as you seal it properly. 