An enterprise wants to build a server system and requires the following functions: 1. The enterprise needs to have its own dedicated mailbox, and the sending and receiving of emails needs to go through the enterprise's server; 2. The server must provide file transfer and access services. Users in different departments of the enterprise provide accounts with different permissions: 3. When the enterprise accesses the internal webpage of the enterprise, the enterprise can directly enter the domain name in the browser to access. To meet the above requirements, which of the following servers do enterprises need to deploy? ( )*

Which of the following types of malicious code on your computer includes?

The trigger modes of the built-in Portal authentication in the firewall include pre-authentication and ____ authentication[fill in the blank]*

IPSec VPN uses an asymmetric algorithm to calculate the ___ key to encrypt data packets.[fill in the blank]

As shown, in transmission mode, which of the following locations should the AH header be inserted in?