For the Huawei USG6000 product, which of the following statements about mail filtering configuration is correct?

Which of the following statements is wrong about HTTP behavior?

What are the risks to information security caused by unauthorized access? (Multiple choices)

Part of the reason why the APT attack becomes difficult to defend is that it uses the vulnerabilities to attack.
This kind of zero-day hole usually requires flowers
A lot of time to research and analyze and produce corresponding defense methods.

Network attacks are mainly divided into two categories: single-packet attacks and streaming attacks.
Single-packet attacks include scanning and snooping attacks, malformed packet attacks, and special reports.
Wen attack.