Received 221g after visa got approved requesting copy of I797

[sandeep_k]

Visa was approved for H1b application during interview. When passport got delivered, received 221g letter along with it. The document required is copy of I797 approval notice.

The first ask in the interview at the consulate was I797, for that showed the original I797 document.
I am curious to know why I797 copy is the query?

Now what would be the time needed for administrative processing for case like this?