1. [多选题]As the Ezonexam network administrator, you are required to have a firm understanding of the OSI model. Why does the data communication industry use the layered OSI reference model? (Choose two)
A. It enables equipment from different vendors to use the same electronic components, thus saving research and development funds
B. It encourages industry standardization by defining what functions occur at each layer of the model
C. It divides the network communication process into smaller and simpler components; thus aiding component development, design and troubleshooting
D. It provides a means by which changes in functionality in one layer require changes in other layers
E. It supports the evolution of multiple competing standards and thus provides business opportunities for equipment manufacturers
2. [单选题]IP地址为：192.168.50.70，掩码为：255.255.255.248，则该IP和掩码结合划分子网时，每个子网的容量为（）
A. 8
B. 4
C. 12
D. 6
