What are two characteristics of GSS?（）

• A、It helps verify end-to-end path availability.
• B、It provides traffic rerouting in case of disaster.
• C、HSRP, GLBP, and VRRP can be clients of GSS.
• D、BGP must be the routing protocol between the distributed data centers.
• E、DNS responsiveness is improved by providing centralized domain management.