According to the Juniper Networks JNCIS-SEC Study Guide, when you set up your command-and-control (C&C) category with Juniper ATP Cloud, all of the feeds will initially have zero objects in them. This is normal, as it can take a few minutes for the feeds to download. No action is required in this scenario and you will notice the feeds start to populate with objects once the download is complete.

The SSL proxy can detect if encryption is being used by looking at the destination port number of the packet. If the port number is 443, then the proxy can assume that the packet is being sent over an encrypted connection. If the port number is different, then the proxy can assume that the packet is not encrypted. For more information, please refer to the Juniper Networks JNCIS-SEC Study Guide.
Reference:
The SSL proxy is a security feature that provides visibility and control over SSL/TLS encrypted traffic. When SSL proxy is enabled, it intercepts SSL/TLS traffic and decrypts it to allow visibility into the content of the encrypted traffic. However, before decrypting the traffic, the SSL proxy must first determine if the traffic is encrypted.
To detect if encryption is being used, the SSL proxy looks at the destination port number. If the destination port number is a known SSL/TLS port (e.g., TCP port 443), the SSL proxy assumes that encryption is being used and intercepts the traffic. If the destination port is not a known SSL/TLS port, the SSL proxy does not intercept the traffic and allows it to pass through the device unmodified.

You have exceeded the maximum files submission for your SRX platform size: This statement is correct because file scanning on SRX300 Series device has a limit on the number of files that can be submitted per minute based on the platform size3. For example, SRX320 has a limit of 10 files per minute3.

Juniper Identity Management Service (JIMS) collects username and device IP addresses from both DNS and Active Directory domain controller event logs. DNS is used to resolve hostnames to IP addresses, while Active Directory domain controller event logs are used to get information about user accounts, such as when they last logged in.