Which of the following options are correct about the NAT policy processing flow? (Multiple Choice)

If the administrator uses the default authentication domain to authenticate a user, you only need to enter a user name when the user logs, if administrators use the newly created authentication domain to authenticate the user, the user will need to enter login "username @ Certified domain name"

In stateful inspection firewall, when opening state detection mechanism, three-way handshake's second packet (SYN + ACK) arrives the firewall. If there is still no corresponding session table on the firewall, then which of the following statement is correct?

When the IPSec VPN tunnel mode is deployed, the AH protocol is used for packet encapsulation. In the new IP packet header field, which of the following parameters does not require data integrity check?

There are various security threats in the use of the server. Which of the following options is not a server security threat?