Q.Dieffienbachia planting
My leaves are browning around the edges. Is this due to too much light ( sun), or watering?
Suggestions?

These articles will help you identify the problem:
https://www.gardeningknowhow.com/plant-problems/environmental/what-causes-brown-edges-on-leaves-of-plant.htm
https://www.gardeningknowhow.com/houseplants/dumb-cane/growing-dumbcane-dieffenbachia.htm
Overwatering is very common in houseplants and less common in plants outdoors. If overwatering is a problem, your Dieffenbachia will show some of the symptoms in this article:
Too much light can cause browning or whitening from sunburn on this plant species, but this is usually all over the leaf or scattered randomly across the leaf, not just on the edges.