Juniper Juniper Certifications JN0-637 Questions & Answers

• Question 21:

  Which two statements are true regarding NAT64? (Choose two.)

  A. An SRX Series device should be in packet-based forwarding mode for IPv4.

  B. An SRX Series device should be in packet-based forwarding mode for IPv6.

  C. An SRX Series device should be in flow-based forwarding mode for IPv4.

  D. An SRX Series device should be in flow-based forwarding mode for IPv6.

  Correct Answer: CD

  NAT64 requires flow-based forwarding for both IPv4 and IPv6 to ensure proper stateful inspection and address translation. Packet-based forwarding does not support the necessary stateful inspection needed for NAT64. For more on NAT64,

  refer to Juniper NAT64 Overview.

  NAT64 allows communication between IPv6 and IPv4 devices by translating IPv6 addresses to IPv4 addresses and vice versa. On Juniper SRX devices, the device's forwarding mode is crucial in how the device processes traffic.

  Flow-based forwarding mode:

  Correct: Option C: For IPv4 traffic in NAT64 configurations, SRX devices should be in flow- based forwarding mode. Flow-based mode means that the device inspects traffic sessions and tracks state, which is essential for proper NAT64

  operations. This mode enables the device to monitor and translate between IPv4 and IPv6 protocols dynamically while maintaining session states. Correct: Option D: Similarly, for IPv6 traffic, the SRX device should also be in flow-based

  mode. Flow-based mode ensures the SRX tracks the IPv6-to-IPv4 translations properly by preserving the state of each connection, ensuring consistent NAT64 operations.

  Packet-based forwarding mode:Packet-based mode is not used for NAT64 operations because it does not provide stateful inspection, which is required for NAT64 to function correctly. Hence, options A and B are incorrect.

  Juniper References:

  Juniper NAT64 Documentation: Discusses how NAT64 functions on SRX devices and specifies the requirement of flow-based mode for both IPv4 and IPv6 traffic when translating between these protocols.

• Question 22:

  You want to bypass IDP for traffic destined to social media sites using APBR, but it is not working and IDP is dropping the session.

  What are two reasons for this problem? (Choose two.)

  A. The session did not properly reclassify midstream to the correct APBR rule.

  B. IDP disable is not configured on the APBR rule.

  C. The application services bypass is not configured on the APBR rule.

  D. The APBR rule does a match on the first packet.

  Correct Answer: AC

  of Answer A (Session Reclassification):

  APBR (Advanced Policy-Based Routing) requires the session to be classified based on the specified rule, which can change midstream as additional packets are processed. If the session was already established before the APBR rule took

  effect, the traffic may not be correctly reclassified to match the new APBR rule, leading to IDP (Intrusion Detection and Prevention) processing instead of being bypassed. This can occur especially when the session was already established

  before the rule change.

  of Answer C (Application Services Bypass):

  For APBR to work and bypass the IDP service, the application services bypass must be explicitly configured. Without this configuration, the APBR rule may redirect the traffic, but the IDP service will still inspect and potentially drop the traffic.

  This is especially important for traffic destined for specific sites like social media platforms where bypassing IDP is desired.

  Example configuration for bypassing IDP services:

  bash

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  set security forwarding-options advanced-policy-based-routing profile application-services- bypass

  Step-by-Step Resolution:

  Reclassify the Session Midstream:

  If the traffic was already being processed before the APBR rule was applied, ensure that the session is reclassified by terminating the current session or ensuring the APBR rule is applied from the start.

  Command to clear the session:

  bash

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  clear security flow session destination-prefix

  Configure Application Services Bypass:

  Ensure that the APBR rule includes the application services bypass configuration to properly bypass IDP or any other security services for traffic that should not be inspected.

  Example configuration:

  bash

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  set security forwarding-options advanced-policy-based-routing profile application-services- bypass

  Juniper Security Reference:

  Session Reclassification in APBR: APBR requires reclassification of sessions in real-time to ensure midstream packets are processed by the correct rule. This is crucial when policies change dynamically or new rules are added. Application

  Services Bypass in APBR: This feature ensures that security services such as IDP are bypassed for traffic that matches specific APBR rules. This is essential for applications where performance is a priority and security inspection is not

  necessary.

• Question 23:

  You are using ADVPN to deploy a hub-and-spoke VPN to connect your enterprise sites.

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

  A. ADVPN creates a full-mesh topology.

  B. IBGP routing is required.

  C. OSPF routing is required.

  D. Certificate-based authentication is required.

  Correct Answer: AC

  ADVPN allows on-demand creation of direct spoke-to-spoke VPN tunnels, effectively enabling a full-mesh topology. OSPF is typically used as the routing protocol for these dynamic connections, as it supports dynamic neighbor discovery and

  can quickly adapt to topology changes. See Juniper ADVPN Overview.

  ADVPN (Auto-Discovery VPN) simplifies the setup of a dynamic VPN for enterprise environments:

  Full Mesh Topology (Answer A): ADVPN dynamically establishes direct, on-demand tunnels between sites (spokes) when required, creating a full-mesh topology without the need for predefined static tunnels. This reduces overhead in huband-spoke topologies by bypassing the hub for inter-spoke traffic.

  OSPF Routing (Answer C): For ADVPN to function, OSPF (Open Shortest Path First) is commonly used as the dynamic routing protocol to advertise routes between the hub and spokes. OSPF ensures that routes are properly propagated for

  dynamic tunnel creation.

  OSPF distributes the necessary routing information, enabling the automatic discovery and setup of VPN tunnels between spokes.

• Question 24:

  You want to test how the device handles a theoretical session without generating traffic on the Junos security device.

  Which command is used in this scenario?

  A. request security policies check

  B. show security flow session

  C. show security match-policies

  D. show security policies

  Correct Answer: A

  The request security policies check command allows you to simulate a session through the SRX device, checking the security policy action that would apply without needing to send real traffic. This helps in validating configurations before

  actual deployment. For more details, see Juniper Security Policies Testing.

  The command request security policies check is used to test how a Junos security device handles a theoretical session without generating actual traffic. This command is useful for validating how security policies would be applied to a session

  based on various parameters like source and destination addresses, application type, and more.

  of Answer A (request security policies check):

  This command allows you to simulate a session and verify which security policies would be applied to the session. It's a proactive method to test security policy configurations without the need to generate real traffic.

  Example usage:

  bash

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  request security policies check from-zone trust to-zone untrust source 10.1.1.1 destination 192.168.1.1 protocol tcp application junos-https

  Juniper Security Reference:

  Security Policies Check: This command provides a way to simulate and verify security policy behavior without actual traffic. Reference: Juniper Security Policy Documentation.

• Question 25:

  You need to set up source NAT so that external hosts can initiate connections to an internal device, but only if a connection to the device was first initiated by the internal device.

  Which type of NAT solution provides this functionality?

  A. Address persistence

  B. Persistent NAT with any remote host

  C. Persistent NAT with target host

  D. Static NAT

  Correct Answer: C

  Persistent NAT with target host allows external hosts to establish connections only when the internal device initiates a session first, ideal for specific interactive applications. Refer to Juniper Persistent NAT Documentation. The scenario requires that external hosts be able to initiate a connectiononly if the internal device has already initiated a connection . The correct solution is Persistent NAT with target host , which ensures that a specific external host can initiate new connections back to the internal device, but only after the internal device has established a session first. Persistent NAT with Target Host (Answer C): This allows the internal device to initiate a connection, and once established, the specified external host can also initiate new connections to the internal device on the same NAT mapping. Example Configuration: bash Copy code set security nat source persistent-nat permit target-host-port This solution is appropriate when controlled bidirectional communication is required based on an internal- initiated connection.

• Question 26:

  An ADVPN configuration has been verified on both the hub and spoke devices and it seems fine. However, OSPF is not functioning as expected.

  

  Referring to the exhibit, which two statements under interface st0.0 on both the hub and spoke devices would solve this problem? (Choose two.)

  A. interface-type p2mp

  B. dynamic-neighbors

  C. passive

  D. interface-type p2p

  Correct Answer: AB

  For ADVPN with OSPF, using a point-to-multipoint (p2mp) interface type and enabling dynamic-neighbors are crucial. This configuration allows dynamic discovery of neighbors and the establishment of tunnels. For more information, refer to

  Juniper ADVPN Configuration Guide.

  In the ADVPN configuration, OSPF isn't functioning as expected due to the interface configuration on st0.0.

  Here are the adjustments needed:

  Interface Type p2mp (Answer A): OSPF requires that the tunnel interface be set to p2mp (point-to- multipoint) to allow OSPF to communicate with multiple dynamic neighbors overthe ADVPN tunnels.

  Command Example:

  bash

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  set interfaces st0.0 family inet ospf interface-type p2mp

  Dynamic Neighbors (Answer B): The dynamic neighbors statement allows OSPF to discover and communicate with dynamically established spokes in an ADVPN environment. This is essential for ADVPN to function properly since the tunnel

  endpoints are not static.

  Command Example:

  bash

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  set protocols ospf area 0.0.0.0 interface st0.0 dynamic-neighbors

  These settings ensure OSPF properly functions over dynamically created ADVPN tunnels.

• Question 27:

  Which two statements are correct about the ICL in an active/active mode multinode HA environment? (Choose two.)

  A. The ICL is strictly a Layer 2 interface.

  B. The ICL uses a separate routing instance to communicate with remote multinode HA peers.

  C. The ICL traffic can be encrypted.

  D. The ICL is the local device management interface in a multinode HA environment.

  Correct Answer: AC

  In an active/active HA environment, the Interchassis Link (ICL) is used primarily for Layer 2 communication between nodes. Encrypting the ICL traffic can enhance security as it carries critical HA state synchronization data. More details can

  be found in the Juniper HA Documentation. In an active/active mode multinode HA (High Availability) setup, the Inter-Chassis Link (ICL) plays a crucial role in connecting SRX Series devices to ensure synchronized operation. Here are the

  key details:

  Layer 2 Interface (Answer A): The ICL operates as a Layer 2 interface, facilitating direct communication between the SRX devices in the HA cluster. This interface is essential for synchronizing session information, firewall states, and

  configuration data across the devices.

  ICL Traffic Encryption (Answer C): For security purposes, the traffic that passes through the ICL can be encrypted. This is particularly important in environments where the ICL traverses insecure or untrusted networks, ensuring that

  synchronization data, including session states and configurations, is protected from interception.

  To configure encryption on ICL, use Junos OS commands to establish secure communication channels and IPsec tunnels if necessary, depending on the network design.

• Question 28:

  Referring to the exhibit.

  

  You have configured a CoS-based VPN that is not functioning correctly. Which action will solve the problem?

  A. You must delete one forwarding class.

  B. You must change the loss priorities of the forwarding classes to low.

  C. You must use inet precedence instead of DSCP.

  D. You must change the code point for the DB-data forwarding class to 10000.

  Correct Answer: A

  In the exhibit, the CoS-based VPN configuration is not functioning correctly due to an issue with the number of forwarding classes. The maximum number of forwarding classes supported for CoS-based VPNs with multiple SAs (security associations) is typically four forwarding classes. In this case, more than four forwarding classes are defined.

  To solve the issue, one forwarding class must be deleted to ensure that the total number of forwarding classes is reduced to four or fewer.

• Question 29:

  Referring to the exhibit.

  

  You are configuring NAT64 on your SRX Series device. You have committed the configuration shown in the exhibit. Unfortunately, the communication with the 10.10.201.10 server is not working. You have verified that the interfaces, security zones, and security policies are all correctly configured.

  In this scenario, which action will solve this issue?

  A. Configure source NAT to translate return traffic from IPv4 address to the IPv6 address of your source device.

  B. Configure proxy-ARP on the external IPv4 interface for the 10.10.201.10/32 address.

  C. Configure proxy-NDP on the IPv6 interface for the 2001:db8::1/128 address.

  D. Configure destination NAT to translate return traffic from the IPv4 address to the IPv6 address of your source device.

  Correct Answer: A

  In the scenario described, you are configuring NAT64, which allows communication between IPv6 and IPv4 networks by translating IPv6 packets to IPv4 and vice versa. The configuration in the exhibit shows an attempt to translate traffic

  coming from the IPv6 address 2001:db8::1/128 and destined for the IPv4 address 10.10.201.10/32.

  However, the issue here is related to the return traffic. For NAT64 to function correctly, you must ensure that the return traffic (from the IPv4 network) is translated back to the original IPv6 source address. Without proper translation of the

  return traffic, the communication will not be successful. In this case, you needsource NAT to handle the return traffic correctly.

  Detailed Solution:

  In NAT64, when traffic originates from an IPv6 network and is translated to IPv4, the return traffic from the IPv4 network must be translated back to the original IPv6 address using source NAT . The source NAT configuration must include

  translation for the return path from IPv4 to IPv6 to ensure bidirectional communication.

  Configuration Example:

  To resolve the issue, you can configure source NAT on the SRX device to handle the translation of the return traffic as follows:

  Configure Source NAT for Return Traffic:You need to configure source NAT on the interface handling the return traffic. This will translate the IPv4 address back to the IPv6 source address.

  Example:

  bash

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  set security nat source rule-set ipv4-source-rule from zone untrust

  set security nat source rule-set ipv4-source-rule to zone trust set security nat source rule-set ipv4-source-rule rule source-nat-translation match source-address 10.10.201.10 /32 set security nat source rule-set ipv4-source-rule rule source-

  nat-translation then source-nat pool ipv6-source- pool

  Ensure Proper Routing and Security Policy Configuration:Make sure that both the IPv4 and IPv6 routes are correctly defined, and that security policies are allowing the return traffic through.

  Use the following commands to verify the NAT and policy configurations:

  bash

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  show security nat source

  show security policies

  By configuring source NAT to translate the return traffic back to IPv6, the communication between the IPv6 host and the IPv4 server should now work correctly.

  Juniper Security Reference:

  NAT64 Overview: This functionality allows IPv6 clients to communicate with IPv4-only servers. For successful translation, NAT64 requires both source NAT and destination NAT to handle the bidirectional traffic. Reference: Juniper Networks

  Documentation on NAT64.

• Question 30:

  Referring to the exhibit.

  

  Which statement is true?

  A. SRG1 is configured in hybrid mode.

  B. The ICL is encrypted.

  C. If SRG1 moves to peer 2, peer 1 will drop packets sent to the SRG1 interfaces.

  D. If SRG1 moves to peer 2, peer 1 will forward packets sent to the SRG1 interfaces.

  Correct Answer: D

  The exhibit describes a Chassis Cluster configuration with high availability (HA) settings. The key information is related to Service Redundancy Group 1 (SRG1) and its failover behavior between the two peers.

  of Answer D (Packet Forwarding after Failover):

  In a typical SRX HA setup with active/backup configuration , if the SRG1 group moves to peer 2 (the backup), peer 1 (previously the active node) will forward packets to peer 2 instead of dropping them. This ensures smooth failover and

  seamless continuation of services without packet loss.

  This behavior is part of the active/backup failover process in SRX chassis clusters, where the standby peer takes over traffic processing without disruption.

  Juniper Security Reference:

  Chassis Cluster Failover Behavior: When a service redundancy group fails over to the backup peer, the previously active peer forwards traffic to the new active node. Reference: Juniper Chassis Cluster Documentation.