enhanced indexing: maintaining same duration as benchmark?

CFA Level III
#1

Please confirm the folliowing:

enhanced indexing compared to benchmark:

Establish different risk exposures while maintaining exactly same duration as the benchmark.

The duration in this case, is it weighted avg portfolio duration (as a whole） or independent bond class duration?

#2

Wt avg duration should be same…

#3

weighted avg portfolio duration matching is the bottomline.