Which action will the SRX Series device take if traffic matches the custom attack object...

The correct answer is A. the action taken is defined in the IDP policy that includes this attack object. The exhibit defines a custom attack object named BGP-DEFEND under the security idp custom-attack hierarchy. The custom object includes metadata such as recommended-action drop, severity critical, and signature match conditions such as BGP update AS-path context and pattern 65501. However, an attack object by itself does not determine the final enforcement behavior. The attack object defines what to match; the IDP policy rule that references the object defines what action to take when that match occurs. Juniper describes attack objects as objects used inside IDP rules to identify malicious activity, while IDP rules include rule actions such as drop-packet, drop-connection, close-client, close-server, recommended, and others.

Option B is wrong because the firewall security policy enables IDP inspection by applying an IDP policy, but the IDP action is not selected directly by the normal security policy. Options C and D are too absolute. Even though the custom object shows recommended-action drop, that is only used if the IDP rule action invokes recommended behavior. Without seeing the IDP policy rule action, you cannot conclude reject or drop. Reference topics: IDP custom attack objects, IDP policy rule actions, recommended action, signature-based attack matching.