The exhibit shows From zone: Trust, To zone: Untrust, which identifies the policy as a zone-based security policy. It also shows the policy action as permit and the application as junos-https, with TCP destination port 443. Therefore, the policy permits HTTPS traffic. The displayed inactivity timeout is 1800 seconds, which is the normal value shown for predefined TCP applications such as HTTPS, so it does not prove a non-default timeout. The exhibit also shows sequence number 1, not sequence number 2, so it is not the second policy in the list. Junos security policies are configured in a from-zone to to-zone context and match traffic by criteria such as source address, destination address, and application before applying the configured action.

From the exhibit output:

Policy Information:

Policy: https-access, action-type: permit

From zone: Trust, To zone: Untrust

Application: junos-https

IP protocol: tcp, Destination port: 443

Inactivity timeout: 1800

Sequence number: 1

Analysis:

Option A: Correct. The default inactivity timeout for flow sessions is 60 seconds for TCP without activity . This policy shows an inactivity timeout of 1800 seconds , which is non-default.

Option B: Incorrect. The policy shows Sequence number: 1, which means it is the first policy , not the second.

Option C: Correct. The policy explicitly matches application junos-https (TCP port 443) and has an action of permit. Therefore, it allows HTTPS traffic.

Option D: Incorrect. This is clearly a zone-based policy , but the question asks for two correct statements. Between the four options, the explicitly correct ones are A and C.

Correct Statements: This security policy uses a non-default inactivity timeout, and this security policy permits HTTPS traffic.

Unified security policies use AppID to classify and control applications based on Layer 7 inspection, including applications nested within trusted services such as HTTP. Juniper documentation states that AppID identifies dynamic or real-time Layer 4 through Layer 7 applications and that dynamic applications can be added to unified security policy match criteria. To use AppID-based control, the SRX must have the required Application Identification feature license and application signature support. Dynamic application objects must then be referenced in the security policy so the firewall can match traffic by application identity rather than only by port or protocol. Unified policies do not have to be created only in the global zone, and disabling the default policy is not required.

Exception traffic is traffic that must be sent from the Packet Forwarding Engine (PFE) to the Routing Engine (RE) for processing, such as routing protocol updates, management traffic, or other control-plane packets. Because the RE is a limited and critical resource, Junos OS implements rate limiting on exception traffic .

The purpose is to prevent denial-of-service (DoS) attacks on the Routing Engine by controlling the amount of traffic directed to it.

This ensures the RE continues to process control-plane operations reliably, even under potential attack or heavy traffic conditions.

Rate limiting does not enhance forwarding plane performance (Option A), simplify interface configuration (Option B), or manage routing protocols directly (Option D).

Routing instances: Security zones are local to their routing instance. They cannot be shared between routing instances (Option B is correct). Each routing instance must define its own zones.

Intrazone and interzone traffic: Both types of traffic require policies in Junos OS. Intrazone traffic must have an explicit intra-zone policy to be controlled (Option C is correct).

Sharing zones: Option A is incorrect, as zones cannot span routing instances.

Multiple zones: SRX devices fully support multiple security zones (trust, untrust, DMZ, etc.). Option D is incorrect.

Correct Statements: B and C

To enforce a catch-all blocking policy after other specific policies, the correct solution is a global security policy (Option A) .

Global policies can apply universally across zones, and an administrator can configure a final “deny all” rule to block any unmatched traffic.

ATP policy (Option B): Protects against advanced threats, not used for catch-all rule enforcement.

IDP policy (Option C): Focuses on intrusion detection and prevention signatures, not general traffic blocking.

Integrated user firewall policy (Option D): Applies policies based on user identity, but it does not provide a universal block across all services.

Correct Solution: Global security policy

The incoming packet shown in the exhibit uses destination port 80, which represents HTTP traffic. The policy table contains entries for FTP, SSH, HTTPS, and ping before the final policy. Because the packet does not match FTP, SSH, HTTPS, or ping, it continues down the ordered policy list until it reaches the final any-any-any deny rule. Junos security policies are evaluated in order, and the first matching policy determines the action for the traffic. This makes option D correct. Since the final matching rule denies the packet, option C is also correct. The packet is not permitted by HTTPS because HTTPS uses TCP destination port 443, not port 80.

Default assignment: All logical interfaces are placed in the null zone by default until explicitly assigned to a user-defined security zone (Option A is correct).

Removal from null zone: Once an interface is assigned to a security zone, it is removed from the null zone (Option D is correct).

No traffic acceptance: The null zone is a discard zone; it cannot be configured to accept any traffic (Option C is incorrect).

Policy behavior: Traffic rejected by a security policy is dropped according to the policy action. It is not forwarded to the null zone for logging (Option B is incorrect).

Correct Statements: A and D

An SRX Series Firewall can operate in flow mode or packet mode. Flow mode is the normal security firewall mode, where the SRX analyzes traffic statefully, creates sessions, and applies services such as security policies, NAT, screens, and application security. Packet mode processes traffic on a per-packet basis and is stateless, making the SRX behave more like a router for selected forwarding functions. Juniper documentation specifically identifies these two operating modes for SRX Series Firewalls. Route mode is not an SRX firewall operating mode; routing is a forwarding function within Junos OS. Wireless mode is also not a firewall processing mode. Therefore, the correct answers are flow mode and packet mode.

Inbound Flow (before NAT): Source = 10.20.30.40 (internal private IP) Destination = 203.0.113.1 (public DNS server)

Outbound Flow (after NAT): Source = 192.0.2.1 (translated IP) Destination = 203.0.113.1 (unchanged)

Analysis:

The source IP (10.20.30.40) was translated to 192.0.2.1 . This indicates Source NAT was applied → Option B is correct .

The destination IP changed between the inbound and outbound view. Inbound it was 203.0.113.1 , and outbound it is still 203.0.113.1 in appearance, but notice the reversal: the session entry shows it as the outbound " source " side. This confirms Destination NAT translation has occurred for return flow consistency → Option D is correct .

Option A: Incorrect. The original source IP was indeed translated.

Option C: Incorrect. The destination IP did change in the flow processing.

Correct Statements:

The original source IP address was translated to a new source IP address.

The original destination IP address was translated to a new destination IP address.