what did Bama first come to know of the social discrimination faced by the people of her community?

The so-called upper-caste people considered people like the narrator and his brother as untouchables and lower-caste. Though they used their labour, they hypocritically avoided their touch. They could never allow to have the untouchables' abode anywhere near them and thus, spaces were segregated according to caste. The landlord's man asking Annan about the street where he resided shows how he was curious to know Annan's caste. Any further communication and its means depended on this one crucial question for the upper-caste. It would determine the upper-caste man's behaviour towards Annan and also the kind of behaviour he would expect from Annan. It is almost like passing a judgement on a person about his dos and don'ts on basis of his caste.The mention of this event in the text is important as it puts to display the discriminatory behaviour of the upper-castes towards the so-called untouchables and how people like the narrator and his brother had to deal with such hindrances even in their common day-to-day lives.