You work as an Exchange Administrator for Xxx Inc.The company has a Windows 2008 Active Directorybased network.The network contains an Exchange Server 2010 organization.The Exchange environment has two Edge Transport servers and two Hub servers.The CTO wants you to filter a list of IP addresses and requests that you add these IP addresses to the block list. You log into one of the Edge Transport servers and add the list of IPs to the block list.The next day the CTO informs you that the IP addresses he gave you are still able to send messages into the Exchange environment. What changes should you make to ensure these IP addresses are blocked？（）

• A、Restart the SMTP service.
• B、Reboot the Edge Transport server.
• C、Add the list to the second Edge Transport server.
• D、Restart IIS.