Stock ROM: Samsung Galaxy A7 SM-A7100 Android 6.0.1 Marshmallow. The firmware available for downloading https://www.sammobile.com/firmwares/database/SM-A7100/. You can download your Samsung Galaxy A7 SM-A7100 firmware at the page, available for some countries. How to Root for Samsung Galaxy A7 SM-A7100 is the separated post, this post only for upgrading to Android 6.0.1 Marshmallow.
Tags: Android 6.0.1 Marshmallow, firmware update, Galaxy A7 SM-A7100, stock rom