多项选择题 Which two types of attacks are considered to be denial of service?（） (Choose two.)

单项选择题 Interface ge-0/0/2.0 of your device is attached to the Internet and is configured with an IP address and network mask of 71.33.252.17/24. A Web server with IP address 10.20.20.1 is running an HTTP service on TCP port 8080. The Web server is attached to the ge-0/0/0.0 interface of your device. You must use NAT to make the Web server reachable from the Internet using port translation. Which type of NAT must you configure?（）

单项选择题 Which encryption type is used to secure user data in an IPsec tunnel?（）