Which of the following actions should he take to ensure that WAF functions correctly and enhance system security?

A customer built his website on Alibaba Cloud- To defend against Web attacks he activated Alibaba Cloud WAF However, a week later, the customer finds that his website has suffered intrusion.

Which of the following actions should he take to ensure that WAF functions correctly and enhance system security? (Number of correct answers: 4)
A . Use Security Center to remove Trojans and fix vulnerabilities
B . Delete all snapshots and clear the server
C . Secure other HTTP services on the ECS instance using WAF
D . Configure a security group for the ECS instance.
E . Check whether or not the DNS resolution results point to the WAF address
F . Resolve the website domain name to the site s source IP address

Answer: A,C,D,E