JNCIA-SEC Monitoring And Troubleshooting Practice Test 5 — 15 Questions

Question 1

Which THREE methods can be used to examine Junos system log files for security events? (Choose three)

Accepted Answer

Using 'monitor start ' to watch log entries in real time. Option A is correct because the operational-mode command 'monitor start ' streams new entries appended to a Junos log file (e.g., /var/log/messages) to the terminal in real time, which is a valid way to observe security events as they occur. Option C is correct because Junos can forward log messages to remote syslog collection servers via the 'host' statement under 'system syslog', and reviewing those aggregated logs on the external server is a legitimate method for examining security events. Option E is correct because 'show log ' from operational mode displays the contents of a specified log file such as messages or interactive-commands, allowing direct inspection of recorded security events. Option B does not belong because 'edit system syslog' only enters configuration mode to define syslog parameters (files, facilities, severities, hosts) and does not itself display or examine log contents. Option D does not belong because 'clear system log' is not a valid command for viewing logs; clearing removes or truncates log data rather than showing it, so it cannot be used to examine security events.

Answer

Running 'edit system syslog' in configuration mode

Answer

Executing 'clear system log' to view file contents

Question 2

Which TWO factors are important when analyzing session table exhaustion issues on an SRX Series firewall? (Choose two)

Accepted Answer

Identifying top sources or application types generating high session volumes. Option C is correct because session table exhaustion is fundamentally caused by high session creation rates, so identifying the top talkers—source IPs, destination IPs, or application types (e.g., via show security flow session summary or session statistics)—pinpoints what is consuming the table and drives mitigation such as application-aware policing or ALGs. Option D is correct because each SRX platform has a documented maximum session capacity (for example, branch SRX models support far fewer sessions than high-end SRX5000 line cards), and knowing that hardware limit tells you whether the table is genuinely exhausted or whether a timeout/aging issue is at play. Option A is not relevant because physical cable integrity affects link up/down and packet loss, not session table occupancy. Option B is not relevant because BGP route convergence timers influence routing stability and reconvergence, not the number of active flow sessions. Option E is not relevant because NTP accuracy affects timestamps, logs, and certificate validity, but it does not directly cause or explain session table exhaustion.

Answer

Checking interface cable physical integrity

Answer

Verifying BGP route convergence timers

Answer

Inspecting NTP time synchronization accuracy

Question 3

Which TWO commands can be used to view IDP configuration status and threat detection statistics? (Choose two)

Accepted Answer

show security idp status. Option A, `show security idp status`, is correct because on Juniper SRX devices this operational command displays the IDP configuration/operational status, including whether IDP is enabled and the policy/rule set state. Option B, `show security idp statistics`, is correct because it reports IDP threat detection statistics such as attack counters and protocol anomaly counts. The remaining options are not valid Junos operational commands for this purpose: `show firewall idp-counters`, `show security flow idp-status`, and `show system idp-status` do not exist in the IDP CLI hierarchy and therefore cannot display IDP configuration status or threat statistics.

Answer

show firewall idp-counters

Answer

show security flow idp-status

Answer

show system idp-status

Question 4

Which THREE checks should be performed when troubleshooting source NAT translation failures? (Choose three)

Accepted Answer

Verify that the source NAT rule is active and correctly applied to the traffic zone. Option A is correct because a source NAT rule must be enabled and matched to the correct traffic zone (source/destination zone and interface) for translation to occur; an inactive or misapplied rule causes translation failures. Option B is correct because security policies must allow the traffic from the source zone to the destination zone before NAT processing can succeed; a denied policy prevents the session and thus the NAT translation. Option D is correct because if the source NAT pool is exhausted (all addresses in use), new sessions cannot be translated and will fail. Option C is not correct because IKE Phase 1 authentication keys relate to IPsec VPN tunnel establishment, not source NAT translation. Option E is not correct because static route metrics affect path selection, not whether source NAT translation itself succeeds.

Answer

Check IKE Phase 1 authentication keys

Answer

Verify that static routing table metrics are set to preferred values

Question 5

Which THREE parameters are typically included in security flow traceoptions output when troubleshooting dropped packets? (Choose three)

Accepted Answer

Packet reception and interface context. Option A is correct because security flow traceoptions output begins with the packet's ingress context, showing the receiving interface, source/destination addresses, and ports so you can confirm the packet actually arrived and on which interface. Option D is correct because the trace records the security policy lookup, including the zone context and the policy that was evaluated and matched (or failed to match), which is essential for understanding how the session was handled. Option E is correct because the trace explicitly logs the drop reason when a packet is discarded, such as a policy deny, a screen violation, or a TCP/IP stack rejection, which directly identifies why the packet did not pass. Option B is not relevant because chassis power supply voltage is hardware/environmental monitoring data, not part of flow traceoptions packet processing. Option C is not relevant because BGP AS path recomputation is a routing protocol event and is not included in security flow traceoptions output.

Answer

Chassis power supply voltage levels

Answer

BGP AS path recomputation steps

Question 6

Which THREE actions are effective when diagnosing intermittent connectivity issues through an SRX firewall where asymmetric routing is suspected? (Choose three)

Accepted Answer

Inspect active sessions using 'show security flow session' to verify session state progression. Option A is correct because 'show security flow session' displays the session table, letting you confirm whether a session is created, whether it reaches the 'Established' state, and whether packets are being forwarded in both directions, which is essential for spotting asymmetric-routing symptoms like one-way or half-open sessions. Option B is correct because flow traceoptions can log packet processing and explicitly show RPF check failures; since asymmetric routing often causes the return packet to arrive on an interface other than the one the route points to, the SRX drops it on the RPF check, and traceoptions reveals this. Option E is correct because when asymmetric routing cannot be eliminated, 'set security flow tcp-session no-syn-check' allows the SRX to accept TCP packets that do not carry the SYN flag, which is necessary when the SYN and subsequent packets traverse different paths/devices and the firewall never sees the initial handshake. Option C is not appropriate because permitting any-to-any traffic does not diagnose or resolve asymmetric routing and needlessly weakens security. Option D is not appropriate because power-cycling the chassis is a disruptive hardware action that has no bearing on a routing or session-flow diagnosis.

Answer

Reconfigure all firewall security policies to permit any-to-any traffic

Answer

Restart the device chassis power supplies

Question 7

An administrator needs to quickly check the number of active sessions currently residing on an SRX Series device to troubleshoot potential memory exhaustion. Which command should be used?

Accepted Answer

show security flow session summary. The command 'show security flow session summary' provides a concise, high-level count of active sessions on an SRX Series device, including total sessions, and often a breakdown by protocol or type. This directly addresses the administrator's need to quickly assess session volume, which is critical when troubleshooting potential memory exhaustion because each session consumes memory resources. Unlike more verbose commands, the summary output is immediate and does not require parsing detailed session lists.

Answer

show system connections

Answer

show security flow statistics

Answer

show security monitoring statistics

Question 8

While troubleshooting a traffic drop between two security zones, an engineer wants to verify which security policy is matching a specific packet flow. Which command provides this troubleshooting capability?

Accepted Answer

show security policy match (source-ip) (destination-ip) (application). 'show security policy match' accepts source-ip, destination-ip, and application parameters and returns which security policy would match that specific flow. This is the purpose-built troubleshooting command for verifying policy selection without generating live traffic.

Answer

show firewall filter match

Answer

show security monitoring policy-match

Answer

test security policy evaluate

Question 9

You suspect that asymmetrical routing is causing packets to be dropped by the Junos security session handler. Which command allows you to view detailed session information, including the expected and received packet direction and interface?

Accepted Answer

show security flow session detail. The command 'show security flow session detail' provides in-depth session information, including the expected and received packet direction and interface. This is crucial for diagnosing asymmetrical routing, as it shows if packets are arriving on the wrong interface or in the wrong direction. The detail option includes fields like 'Incoming interface' and 'Outgoing interface' for both directions, allowing you to verify session symmetry.

Answer

show security flow session summary

Answer

show security flow node 0 session

Answer

show security flow session interface

Question 10

An administrator enables security flow traceoptions to debug a packet drop. The log file shows the drop reason as "No session found; policy check failed". What is the most likely cause of this error?

Accepted Answer

The packet is the first packet of a new flow, and no matching security policy permits the traffic.. When a packet does not match an existing session, the SRX evaluates security policies. If no policy permits the traffic, a drop occurs with an explicit policy check failure message.

Answer

NAT pool exhaustion prevented session creation.

Answer

The session table is full and cannot allocate memory for a new session.

Answer

The packet belongs to an established TCP connection whose sequence number was invalid.

Question 11

An engineer is troubleshooting a potential Denial of Service (DoS) attack. They want to check if screen options have dropped any packets on a specific security zone. Which command should be used?

Accepted Answer

show security screen statistics zone . The command 'show security screen statistics zone ' displays screen option drop counters for a specific security zone, allowing the engineer to see exactly which screen checks (SYN flood, ICMP flood, etc.) have dropped packets in that zone. This is the precise command for troubleshooting screen-related drops on a per-zone basis.

Answer

show security attack statistics

Answer

show firewall log

Answer

show security flow screen-drops

Question 12

During session table analysis, you notice a session stuck in the 'SynSent' state. What does this state indicate about the traffic flow?

Accepted Answer

The SRX has received a SYN packet from the source, but no SYN-ACK has been returned from the destination.. In Junos security flow, TCP session states track the handshake. SynSent indicates the SRX has seen a TCP SYN packet from the client, but has not yet seen the SYN-ACK from the server.

Answer

The TCP session has timed out and is waiting to be purged from memory.

Answer

The server has reset the connection via a RST packet.

Answer

The three-way handshake has completed successfully and data transfer is underway.

Question 13

You are troubleshooting an issue where an application timeout occurs intermittently. You suspect that session timeouts might be too short for this specific application. Where can you adjust TCP session timeout values globally on an SRX Series device?

Accepted Answer

[edit security flow timeout]. The correct location to adjust TCP session timeout values globally on an SRX Series device is under the [edit security flow timeout] hierarchy. This configuration stanza allows you to set global timeouts for various session types, including TCP, UDP, ICMP, and others. By modifying the TCP timeout value here, you affect all sessions that do not have a more specific timeout defined elsewhere, such as in an application definition. This is the standard method for tuning session timeouts to prevent premature termination of long-lived or idle applications.

Answer

[edit security policies timeout]

Answer

[edit applications session-timeout]

Answer

[edit system services timeout]

Question 14

An administrator needs to monitor CPU and memory utilization of the Routing Engine and Forwarding Plane on an SRX device. Which command provides this hardware health overview?

Accepted Answer

show system resources. The 'show system resources' command displays CPU and memory utilization for both the Routing Engine and the Forwarding Plane (if applicable) on SRX devices. It provides a snapshot of current resource usage, including load averages, memory usage, and process information, making it the correct command for a hardware health overview.

Answer

show chassis hardware

Answer

show security flow status

Answer

show security monitoring resources

Question 15

While analyzing packet flow using security flow traceoptions, you see the message: "ALG: and AlgOpen() failed". What does this indicate?

Accepted Answer

The Application Layer Gateway failed to allocate necessary resources or set up dynamic data channels.. The message 'ALG: and AlgOpen() failed' indicates that the Application Layer Gateway (ALG) failed to allocate resources or set up dynamic data channels. ALGs are responsible for handling protocols that embed IP addresses or ports in the payload (e.g., FTP, SIP) and require dynamic pinholes. This failure means the ALG could not perform its function, often due to resource exhaustion or configuration issues.

Answer

The primary security policy denied the initial control connection.

Answer

The NAT pool was exhausted during source translation.

Answer

The destination host refused the TCP connection via a RST packet.