Hi @Kiran Kumar R
This sounds like the expected behavior of the board. The Specification (Consumer Edition (CE)) clearly allows for this behavior on page 8 and further shows a block diagram on Page 23.
When you plug a cable into the micro-USB port, it disables the two Type-A ports (and the fourth port on the high speed connector).
Full Disclosure: I am an employee of Qualcomm Canada, any opinions I might have expressed may not reflect the opinions of my employer.