单项选择题 A client host uses IPv4 to communicate with one ser ver and IPv6 to communicate with another.Which of the following IPv6 coexistence features is likely at work on the host?（）

单项选择题 An enterprise has plans to start adding IPv6 support. The initial deployment requires support from some IPv6 - only device s that need to access servers that support only IPv4. Which of the following tools would be most appropriate?（）

单项选择题 An enterprise h as plans to start adding IPv6 support. For the first year, the IPv6 will be in small pockets spread around the existing large IPv4 network, with occasional IPv6 traffic while applications teams test IPv6 - enabled servers and applications. Which of the fol lowing tools would be most appropriate?（）