Alibaba Cloud Content Delivery Network (CDN) is a distributed network that is built and overlaid on the bearer network Moreover it is composed of edge node server clusters distributed across different regions. It replaces the traditional data transmission mode, which is centered on Web servers. When using Alibaba Cloud CDN, a user's request wilt first reach the edge node, and then receive data from the origin site by means of back-to-source Moreover, the admin can obtain visitor's real IP on the origin site. Which of the following descriptions relate to "obtaining visitors real IP" are correct? (Number of correct answers: 2)