单项选择题 A service provider wants to prevent the repeat of a denial of service (DoS) attack that recently disabled Internet access for several thousand customers. Which Cisco solution best matches this business need?（）

多项选择题 You are the network consultant from passguide.com. In which situation you will advice your customer to implement data centers?（）

单项选择题 What is a benefit of Internet protocol (IP) telephony?（）