Juniper Juniper Certifications JN0-637 Questions & Answers

• Question 1:

  Which two statements are true when setting up an SRX Series device to operate in mixed mode? (Choose two.)

  A. A physical interface can be configured to be both a Layer 2 and a Layer 3 interface at the same time.

  B. User logical systems support Layer 2 traffic processing.

  C. The SRX must be rebooted after configuring at least one Layer 3 and one Layer 2 interface.

  D. Packets from Layer 2 interfaces are switched within the same bridge domain.

  Correct Answer: CD

  In mixed mode, SRX devices can simultaneously handle Layer 2 switching and Layer 3 routing, but a reboot is required when configuring Layer 2 and Layer 3 interfaces to ensure the configuration takes effect. Layer 2 packets are switched

  within the defined bridge domain. Further guidance on SRX mixed mode can be found at Juniper Mixed Mode Documentation.

  When an SRX Series device is configured in mixed mode , both Layer 2 switching and Layer 3 routing functionalities can be used on the same device. This enables the SRX to act as both a router and a switch for different interfaces.

  However, there are certain considerations:

  of Answer C (Reboot Requirement):

  After configuring the SRX to operate with at least one Layer 2 interface and one Layer 3 interface, the device needs to be rebooted. This is required to properly initialize the mixed mode configuration, as the SRX needs to switch between

  Layer 2 and Layer 3 processing modes.

  of Answer D (Layer 2 Traffic Handling):

  In mixed mode, traffic from Layer 2 interfaces is switched within the same bridge domain . A bridge domain defines a Layer 2 broadcast domain, and packets from Layer 2 interfaces are forwarded based on MAC addresses within that domain.

  Juniper Security Reference:

  Mixed Mode Overview: Juniper SRX devices can operate in mixed mode to handle both Layer 2 and Layer 3 traffic simultaneously. Reference: Juniper Mixed Mode Documentation.

• Question 2:

  The exhibit shows part of the flow session logs.

  

  Which two statements are true in this scenario? (Choose two.)

  A. The existing session is found in the table, and the fast path process begins.

  B. This packet arrives on interface ge-0/0/4.0.

  C. Junos captures a TCP packet from source address 172.20.101.10 destined to 10.0.1.129.

  D. Destination NAT occurs.

  Correct Answer: BC

  From the session log, we can derive the following:

  Packet arrives on ge-0/0/4.0 (Answer B): The log indicates that the incoming packet is being processed on the ge-0/0/4.0 interface, as seen in the output.

  Example Log Analysis:

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  CID-0:THREAD_ID-01:RT: chose interface ge-0/0/4.0 as incoming nat if.

  TCP Packet Captured (Answer C): The source of the packet is 172.20.101.10 and it is destined for 10.0.1.129 on port 22, as described in the log.

  Example Log Analysis:

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  CID-0:THREAD_ID-01:RT: CID-0:THREAD_ID-01:RT: flow_first_create_session...

  sa 172.20.101.10, da 10.0.1.129, sp 59009, dp 22

  These logs show the creation of a session for TCP traffic (likely SSH, based on port 22) between the source and destination addresses across the tunnel.

• Question 3:

  You are using trace options to troubleshoot a security policy on your SRX Series device.

  

  Referring to the exhibit, which two statements are true? (Choose two.)

  A. The SSH traffic matches an existing session.

  B. No entries are created in the SRX session table.

  C. The traffic is not destined for the root logical system.

  D. The security policy controls traffic destined to the SRX device.

  Correct Answer: BD

  The trace indicates that no session entry was created, suggesting a policy deny. The security policy affects control plane traffic heading to the SRX, not just transit traffic. Additional guidance can be found in Juniper Traceoptions and Security

  Policies.

  In the trace options output provided, we observe the following details:

  No Entries in Session Table (Correct: Option B):The trace shows a message indicating the packet was dropped with the cause "policy deny-ssh." This means that the SSH traffic was denied by a security policy before a session could be

  created in the session table. Therefore, no session entries were recorded for this traffic, which aligns with the output where traffic is blocked at the policy evaluation stage.

  Security Policy Controls Traffic to SRX (Correct: Option D):The policy search in the trace log shows the traffic is being denied by a policy, and the destination is the SRX itself (zone junos-host). This implies that the security policy is controlling

  inbound traffic to the SRX device's control plane. In this case, SSH traffic was denied by a policy designed to protect the control plane.

  Juniper References:

  Juniper Trace Options Documentation: Provides detailed explanation of trace options output and how to interpret policy evaluation and session creation in SRX devices.

• Question 4:

  Referring to the exhibit,

  

  Which statement about TLS 1.2 traffic is correct?

  A. TLS 1.2 traffic will be sent to routing instance R1 but not forwarded to the next hop.

  B. TLS 1.2 traffic will be sent to routing instance R1 and forwarded to next hop 10.1.0.1.

  C. TLS 1.2 traffic will be sent to routing instance R2 but not forwarded to the next hop.

  D. TLS 1.2 traffic will be sent to routing instance R2 and forwarded to next hop 10.2.0.1.

  Correct Answer: B

  The configuration in the exhibit shows an advanced-policy-based-routing (APBR) profile that directs traffic based on application type. Specifically:

  Rule Web-Proxymatches HTTP and HTTPS (TLS 1.2) traffic and forwards it to routing instance R1 .

  The routing-instance R1 has a static route to send traffic to the next hop 10.1.0.1 .

  Given this configuration, TLS 1.2 traffic, which is part of the HTTPS category, will be sent to routing instance R1 and then forwarded to the next hop IP address 10.1.0.1 .

• Question 5:

  You have deployed automated threat mitigation using Security Director with Policy Enforcer, Juniper ATP Cloud, SRX Series devices, Forescout, and third-party switches. In this scenario, which device is responsible for communicating directly to the third-party switches when infected hosts need to be blocked?

  A. Forescout

  B. Policy Enforcer

  C. Juniper ATP Cloud

  D. SRX Series device

  Correct Answer: A

  In the described scenario, Forescout is responsible for communicating with the third-party switches to enforce mitigation actions when infected hosts are detected. Forescout integrates with Policy Enforcer and other network security products to provide dynamic network access control. When an infected host is detected by Juniper ATP Cloud or SRX devices, Forescout interacts with the switches to enforce the quarantine or block policy, ensuring that the compromised device is isolated from the network.

  Forescout manages the access control lists (ACLs) or other blocking mechanisms on the third-party switches, while Policy Enforcer coordinates with different systems like SRX devices and ATP Cloud for real-time threat mitigation.

• Question 6:

  Referring to the exhibit.

  

  Host A shown in the exhibit is attempting to reach the Web1 webserver, but the connection is failing. Troubleshooting reveals that when Host A attempts to resolve the domain name of the server (web.acme. com), the request is resolved to the private address of the server rather than its public IP.

  Which feature would you configure on the SRX Series device to solve this issue?

  A. Persistent NAT

  B. Double NAT

  C. DNS doctoring

  D. STUN protocol

  Correct Answer: C

  DNS doctoring modifies DNS responses for hosts behind NAT devices, allowing them to receive the correct public IP address for internal resources when queried from the public network. This prevents issues where private IPs are returned

  and are not reachable externally. For details, visit Juniper DNS Doctoring Documentation.

  In this scenario, Host A is trying to resolve the domain name web.acme.com , but the DNS resolution returns the private IP address of the web server instead of its public IP. This is a common issue in networks where private addresses are

  used internally, but public addresses are required for external clients.

  of Answer C (DNS Doctoring):

  DNS doctoringis a feature that modifies DNS replies as they pass through the SRX device. In this case, DNS doctoring can be used to replace the private IP address returned in the DNS response with the correct public IP address for Host A.

  This allows external clients to reach internal resources without being aware of their private IP addresses.

  Configuration Example:

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  set security nat dns-doctoring from-zone untrust to-zone trust

  Juniper Security Reference:

  DNS Doctoring Overview: DNS doctoring is used to modify DNS responses so that external clients can access internal resources using public IP addresses. Reference: Juniper DNS Doctoring Documentation.

• Question 7:

  You have configured the backup signal route IP for your multinode HA deployment, and the ICL link fails. Which two statements are correct in this scenario? (Choose two.)

  A. The current active node retains the active role.

  B. The active node removes the active signal route.

  C. The backup node changes the routing preference to the other node at its medium priority.

  D. The active node keeps the active signal route.

  Correct Answer: AD

  In multinode HA, the active node retains its role and maintains the active signal route even if the ICL link fails, as long as a backup signal route IP is configured. This backup ensures continuity in failover scenarios. For detailed information,

  refer to Juniper Multinode HA Documentation.

  In a multinode HA (High Availability) deployment with SRX devices, the Inter-Chassis Link (ICL) is critical for communication between the active and backup nodes. If the ICL link fails, the system relies on thebackup signal route to continue

  monitoring the state of the HA deployment.

  of Answer A (Active Node Retains Active Role):

  If the ICL link fails but the backup signal route is still operational, the active node will retain its role as the active node. This is because the signal route allows the active node to confirm its operational state.

  of Answer D (Active Node Keeps Signal Route):

  The active node will maintain the signal route if the backup signal route remains operational. The backup node will not preemptively take over the active role unless it detects that the active node has failed entirely.

  Juniper Security Reference:

  Multinode HA Overview: The backup signal route in multinode HA ensures that the active node retains control as long as it can maintain a signal route. Reference: Juniper HA Documentation.

• Question 8:

  Which role does an SRX Series device play in a DS-Lite deployment?

  A. Softwire concentrator

  B. STUN server

  C. STUN client

  D. Softwire initiator

  Correct Answer: D

  In a DS-Lite deployment, the SRX device functions as the softwire initiator, which initiates IPv4-in-IPv6 tunneling to connect IPv4 hosts over an IPv6 infrastructure. For DS-Lite configurations and roles, check Juniper DS-Lite Documentation.

  In a DS-Lite (Dual-Stack Lite) deployment, the SRX Series device typically acts as a softwire initiator. DS- Lite is an IPv6 transition technology that allows IPv6-enabled devices to communicate with IPv4 networks.

  The softwire initiator is responsible for encapsulating IPv4 packets within an IPv6 header at the customer edge, which is then sent to the softwire concentrator (usually on the service provider's side). Juniper SRX devices can be configured for

  DS-Lite to support IPv6 clients while communicating with an IPv4 internet via this tunneling mechanism.

  To configure DS-Lite on a Juniper SRX device, you'd follow these steps:

  Configure the DS-Lite AFTR (Address Family Transition Router) with the correct IPv6 addressing and routing parameters.

  Enable DS-Lite functionality on the SRX device using Junos OS commands.

  Verify connectivity and ensure that traffic from IPv6 devices is correctly tunneled over IPv4 using tools like ping and traceroute over IPv6.

• Question 9:

  How does an SRX Series device examine exception traffic?

  A. The device examines the host-inbound traffic for the ingress interface and zone.

  B. The device examines the host-outbound traffic for the ingress interface and zone.

  C. The device examines the host-inbound traffic for the egress interface and zone.

  D. The device examines the host-outbound traffic for the egress interface and zone.

  Correct Answer: A

  Exception traffic, including management and control plane traffic, is handled by examining host-inbound traffic configurations at the ingress interface and zone. It ensures traffic reaches necessary services like SSH and IKE securely. See

  Juniper Host Inbound Traffic Documentation for more.

  SRX Series devices handle exception traffic (such as management traffic like SSH, Telnet, DNS queries, etc.) differently than regular transit traffic. Exception traffic is examined based onhost-inbound traffic for the ingress interface and zone .

  If traffic is destined for the device itself (e.g., management traffic or routing protocol messages), it must be allowed as host-inbound traffic on both the ingress interface and zone.

  Example Command:

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  set security zones security-zone trust host-inbound-traffic system-services ssh

  This ensures that traffic destined to the SRX device is inspected based on the ingress interface and zone.

• Question 10:

  Referring to the exhibit.

  

  You have deployed an SRX Series device as shown in the exhibit. The devices in the Local zone have recently been added, but their SRX interfaces have not been configured. You must configure the SRX to meet the following requirements:

  1.

  Devices in the 10.1.1.0/24 network can communicate with other devices in the same network but not with other networks or the SRX.

  2.

  You must be able to apply security policies to traffic flows between devices in the Local zone. Which three configuration elements will be required as part of your configuration? (Choose three.)

  A. set security zones security-zone Local interfaces ge-0/0/1.0

  B. set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan-members 10

  C. set protocols l2-learning global-mode switching

  D. set protocols l2-learning global-mode transparent-bridge

  E. set security zones security-zone Local interfaces irb.10

  Correct Answer: ABD

  In this scenario, we need to configure the SRX Series device so that devices in the Local zone (VLAN 10, 10.1.1.0/24 network) can communicate with each other but not with other networks or the SRX itself. Additionally, you must be able to apply security policies to traffic flows between the devices in the Local zone.

  of Answer A (Assigning Interface to Security Zone):

  You need to assign the interface ge-0/0/1.0 to the Local security zone. This is crucial because the SRX only applies security policies to interfaces assigned to security zones. Without this, traffic between devices in the Local zone won't be

  processed by security policies.

  Configuration:

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  set security zones security-zone Local interfaces ge-0/0/1.0

  of Answer B (Configuring Ethernet-Switching for VLAN 10):

  Since we are using Layer 2 switching between devices in VLAN 10, we need to configure the interface to operate in Ethernet switching mode and assign it toVLAN 10.

  Configuration:

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  set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan-members 10

  of Answer D (Transparent Bridging Mode for Layer 2):

  The global mode for Layer 2 switching on the SRX device must be set to transparent-bridge . This ensures that the SRX operates in Layer 2 mode and can switch traffic between devices without routing.

  Configuration:

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  set protocols l2-learning global-mode transparent-bridge

  Summary:

  Interface Assignment: Interface ge-0/0/1.0 is assigned to the Local zone to allow policy enforcement.

  Ethernet-Switching: The interface is configured for Layer 2 Ethernet switching in VLAN 10.

  Transparent Bridging: The SRX is configured in Layer 2 transparent-bridge mode for switching between devices.

  Juniper Security Reference:

  Layer 2 Bridging and Switching Overview: This mode allows the SRX to act as a Layer 2 switch for forwarding traffic between VLAN members without routing. Reference: Juniper Transparent Bridging Documentation.