Juniper Juniper Certifications JN0-637 Questions & Answers

• Question 31:

  A company has acquired a new branch office that has the same address space of one of its local networks, 192.168.100/24. The offices need to communicate with each other.

  Which two NAT configurations will satisfy this requirement? (Choose two.)

  A. [edit security nat source] user@OfficeA# show rule-set OfficeBtoA { from zone OfficeB; to zone OfficeA; rule 1 { match { source-address 192.168.210.0/24; destination-address 192.168.200.0/24; } then { source-nat { interface; } } } }

  B. [edit security nat static] user@OfficeA# show rule-set From-Office-B { from interface ge-0/0/0.0; rule 1 { match { destination-address 192.168.200.0/24; } then { static-nat { prefix 192.168.100.0/24; } } } }

  C. [edit security nat static] user@OfficeB# show rule-set From-Office-A { from interface ge-0/0/0.0; rule 1 { match { destination-address 192.168.210.0/24; } then { static-nat { prefix 192.168.100.0/24; } } } }

  D. [edit security nat source] user@OfficeB# show rule-set OfficeAtoB { from zone OfficeA; to zone OfficeB; rule 1 { match { source-address 192.168.200.0/24; destination-address 192.168.210.0/24; } then { source-nat { interface; } } } }

  Correct Answer: AD

  The problem describes two offices needing to communicate, but both share the same IP address space, 192.168.100.0/24. To resolve this, NAT must be configured to translate the conflicting address spaces on each side. Here's how each of

  the configurations works:

  Option A (Correct):This source NAT rule translates the source address of traffic from Office B to Office A . By configuring source NAT, the source IP addresses from Office B (192.168.210.0/24) will be translated when communicating with

  Office A (192.168.200.0/24). This method ensures that there is no overlap in address space when packets are transmitted between the two offices. Option D (Correct):This is a source NAT rule configured on Office B , which translates the

  source addresses from Office A to prevent address conflicts. It ensures that when traffic is initiated from Office A Office B to , the overlapping address range (192.168.100.0/24) is translated.

  Options B and C (Incorrect):These options involve static NAT rules that map address ranges between the two offices, but they do not resolve the overlapping IP address space issue effectively. Static NAT is not the optimal solution in this

  scenario since the problem involves address space conflict, which requires translation of source addresses during communication.

  Juniper References:

  Juniper NAT Configuration Guide: Detailed instructions on how to configure source NAT and resolve address conflicts between networks.

• Question 32:

  Which two statements are true about the procedures the Junos security device uses when handling traffic destined for the device itself? (Choose two.)

  A. If the received packet is addressed to the ingress interface, then the device first performs a security policy evaluation for the junos-host zone.

  B. If the received packet is destined for an interface other than the ingress interface, then the device performs a security policy evaluation for the junos-host zone.

  C. If the received packet is addressed to the ingress interface, then the device first examines the host- inbound-traffic configuration for the ingress interface and zone.

  D. If the received packet is destined for an interface other than the ingress interface, then the device performs a security policy evaluation based on the ingress and egress zone.

  Correct Answer: BC

  When handling traffic that is destined for itself, the SRX examines the host-inbound-trafficconfiguration for the ingress interface and the associated security zone. It evaluates whether the traffic should be allowed based on this configuration.

  Traffic not addressed to the ingress interface is handled based on security policies within the junos-host zone, which applies to traffic directed to the SRX itself. For more details, refer to Juniper Host Inbound Traffic Documentation.

  When handling traffic that is destined for the SRX device itself (also known as host-bound traffic ), the SRX follows a specific process to evaluate the traffic and apply the appropriate security policies. Thejunos-host zone is a special security

  zone used for managing traffic destined for the device itself, such as management traffic (SSH, SNMP, etc.).

  of Answer B (Packet to a Different Interface):

  If the packet is destined for an interface other than the ingress interface , the SRX performs a security policy evaluation specifically for the junos-host zone. This ensures that management or host-bound traffic is evaluated according to the

  security policies defined for that zone.

  of Answer C (Packet to the Ingress Interface):

  If the packet is addressed to the ingress interface , the device first checks the host-inbound-traffic configuration for the ingress interface and zone. This configuration determines whether certain types of traffic (such as SSH, HTTP, etc.) are

  allowed to reach the device on that specific interface.

  Step-by-Step Handling of Host-Bound Traffic:

  Host-Inbound Traffic: Define which services are allowed to the SRX device itself:

  bash

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

  Security Policy for junos-host: Ensure policies are defined for managing traffic destined for the SRX device:

  bash

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  set security policies from-zone to-zone junos-host policy allow-ssh match source-address any

  set security policies from-zone to-zone junos-host policy allow-ssh match destination-address any

  Juniper Security Reference:

  Junos-Host Zone: This special zone handles traffic destined for the SRX device, including management traffic. Security policies must be configured to allow this traffic. Reference: Juniper Networks Host-Inbound Traffic Documentation.

• Question 33:

  Your IPsec tunnel is configured with multiple security associations (SAs). Your SRX Series device supports the CoS-based IPsec VPNs with multiple IPsec SAs feature. You are asked to configure CoS for this tunnel. Which two statements are true in this scenario? (Choose two.)

  A. The local and remote gateways do not need the forwarding classes to be defined in the same order.

  B. A maximum of four forwarding classes can be configured for a VPN with the multi-sa forwarding- classes statement.

  C. The local and remote gateways must have the forwarding classes defined in the same order.

  D. A maximum of eight forwarding classes can be configured for a VPN with the multi-sa forwarding- classes statement.

  Correct Answer: CD

  When configuring CoS for an IPsec tunnel with multiple security associations (SAs):

  Forwarding Classes Order (Answer C): Both the local and remote SRX devices must have the same forwarding classes defined in the same order to ensure proper traffic classification and SA mapping. If not aligned, traffic classification can

  fail.

  Command Example:

  bash

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  set security ipsec vpn vpn_name multi-sa forwarding-classes [class1 class2 ...]

  Maximum Forwarding Classes (Answer D): The multi-sa forwarding-classes statement allows up to eight forwarding classes. This is the maximum number of traffic classes that can be differentiated within a single VPN tunnel.

  Command Example:

  bash

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  set security ipsec vpn vpn_name multi-sa forwarding-classes [class1 class2 class3 class4 class5 class6 class7 class8]

• Question 34:

  Referring to the exhibit,

  

  which two statements about User1 are true? (Choose two.)

  A. User1 has access to the configuration specific to their assigned logical system.

  B. User1 is logged in to logical system LSYS-1.

  C. User1 can add logical units to an interface that a primary administrator has not previously assigned.

  D. User1 can view outputs from other user logical systems.

  Correct Answer: AB

  In this configuration, User1 is logged into logical system LSYS-1, which restricts access and visibility to that particular system. This ensures isolation between logical systems on the same physical device. Only a system administrator can

  assign additional permissions. For more details, see Juniper Logical Systems Guide.

  From the exhibit, we see that User1 is logged into logical system LSYS-1 :

  Access to Assigned Logical System (Answer A): User1, being logged into the logical system LSYS-1 , only has access to the configuration and interfaces within that logical system. This is a key feature of logical systems in Junos, ensuring

  users are restricted to their respective environments.

  Logged into LSYS-1 (Answer B): The prompt shows that User1 is currently operating in LSYS-1 , as indicated by the User1@SRX:LSYS-1> command line.

• Question 35:

  Referring to the exhibit.

  

  You are asked to ensure that Internet users can access the company's internal webserver using its FQDN.

  However, the internal DNS server's A record only points to the webserver's private address.

  Referring to the exhibit, which two actions are required to complete this task? (Choose two.)

  A. Disable the DNS ALG.

  B. Configure static NAT for both the DNS server and the webserver.

  C. Configure destination NAT for both the DNS server and the webserver.

  D. Configure proxy ARP on ge-0/0/3.

  Correct Answer: BD

  In the scenario where internal users are trying to access the company's web server via its FQDN but the DNS server resolves to a private IP, two key actions are needed:

  Static NAT (Answer B): Since the internal DNS server resolves the web server to its private IP address (10.10.10.4/24), you need to configure static NAT for both the DNS server and the webserver. This will ensure that requests coming from the internet will be translated to the web server's public IP (203.0.113.4) and the DNS server's public IP (203.0.113.2). Example Command: bash Copy code set security nat static rule-set public-to-private from zone untrust set security nat static rule-set public-to-private rule dns-server match destination-address 203.0.113.2/32 set security nat static rule-set public-to-private rule dns-server then static-nat-prefix 10.10.10.2/32 set security nat static rule-set public-to-private rule web-server match destination-address 203.0.113.4/32 set security nat static rule-set public-to-private rule web-server then static-nat-prefix 10.10.10.4/32 Proxy ARP (Answer D): The SRX needs to respond to ARP requests for the public IP addresses of both the DNS and webserver on the interface facing the internet (ge-0/0/3). This allows the SRX to handle requests directed at the public IPs. Example Command: bash Copy code set interfaces ge-0/0/3 unit 0 family inet proxy-arp interface-address 203.0.113.2/32 set interfaces ge-0/0/3 unit 0 family inet proxy-arp interface-address 203.0.113.4/32 These two configurations allow external users to access the internal web server via its public IP, as resolved by the DNS server.

• Question 36:

  What are three core components for enabling advanced policy-based routing? (Choose three.)

  A. Filter-based forwarding

  B. Routing options

  C. Routing instance

  D. APBR profile

  E. Policies

  Correct Answer: ACD

  To enable Advanced Policy-Based Routing (APBR) on SRX Series devices, three key components are necessary: filter-based forwarding, routing instances, and APBR profiles. Filter-based forwarding is utilized to direct specific traffic flows to

  a routing instance based on criteria set by a policy. Routing instances allow the traffic to be managed independently of the main routing table, and APBR profiles define how and when traffic should be forwarded. These elements ensure that

  APBR is flexible and tailored to the network's requirements. Refer to Juniper's APBR Documentation for more details.

  Advanced policy-based routing (APBR) in Juniper's SRX devices allows the selection of different paths for traffic based on policies, rather than relying purely on routing tables. To enable APBR, the following core components are required:

  Filter-based Forwarding (Answer A):Filter-based forwarding (FBF) is a technique used to forward traffic based on policies rather than the default routing table. It is essential for enabling APBR, as it helps match traffic based on filters and

  directs it to specific routes.

  Configuration Example:

  bash

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  set firewall family inet filter FBF match-term source-address 192.168.1.0/24

  set firewall family inet filter FBF then routing-instance custom-routing-instance

  Routing Instance (Answer C):A routing instance is required to define the separate routing table used by APBR. You can create multiple routing instances and assign traffic to these instances based on policies. The traffic will then use the

  routes defined within the specific routing instance.

  Configuration Example:

  bash

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  set routing-instances custom-routing-instance instance-type forwarding

  set routing-instances custom-routing-instance routing-options static route 0.0.0.0/0 next-hop 10.10.10.1

  APBR Profile (Answer D):The APBR profile defines the rules and policies for advanced policy-based routing. It allows you to set up conditions such as traffic type, source/destination address, and port, and then assign actions such as

  redirecting traffic to specific routing instances.

  Configuration Example:

  bash

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  set security forwarding-options advanced-policy-based-routing profile apbr-profile match application http

  set security forwarding-options advanced-policy-based-routing profile apbr-profile then routing-instance custom-routing-instance Other Components:

  Routing Options (Answer B)are not a core component of APBR, as routing options define the general behavior of the routing table and protocols. However, APBR works by overriding these default routing behaviors using policies. Policies

  (Answer E)are crucial in many network configurations but are not a core component of enabling APBR. APBR specifically relies on profiles rather than standard security policies.

  Juniper Security Reference:

  Advanced Policy-Based Routing (APBR): Juniper's APBR is a powerful tool that allows routing based on specific traffic characteristics rather than relying on static routing tables. APBR ensures that specific types of traffic can take alternate

  paths based on business or network needs. Reference: Juniper Networks APBR Documentation.

• Question 37:

  Referring to the exhibit.

  

  Which two statements are correct? (Choose two.)

  A. The packet is dropped by the default security policy.

  B. The packet is dropped by a configured security policy.

  C. The data shown requires a traceoptions flag of host-traffic.

  D. The data shown requires a traceoptions flag of basic-datapath.

  Correct Answer: AD

  Understanding the Flow Log Output:

  From the flow logs in the exhibit, we can observe the following key events:

  The session creation was initiated (flow_first_create_session), but the policy searchfailed (flow_first_policy_search), which implies that no matching policy was found between the zones involved (zone trust-> zone dmz). The packet was

  dropped with the reason "denied by policy." This shows that the packet was dropped either due to no matching security policy or because the default policy denies the traffic (packet dropped, denied by policy). The line denied by policy

  default-policy-logical-system-00(2) indicates that the default security policy is responsible for denying the traffic, confirming that no explicit security policy was configured to allow this traffic.

  of Answer A (Dropped by the default security policy):

  The log message clearly states that the packet was dropped by the default security policy (default-policy- logical-system-00). In Junos, when a session is attempted between two zones and no explicit policy exists to allow the traffic, the default

  policy is to deny the traffic. This is a common behavior in Junos OS when a security policy does not explicitly allow traffic between zones.

  of Answer D (Requires traceoptions flag of basic-datapath):

  The information displayed in the log involves session creation, flow policy search, and packet dropping due to policy violations, which are all part of basic packet processing in the data path. This type of information is logged when the

  traceoptions flag is set to basic-datapath . The basic-datapath traceoption provides detailed information about the forwarding process, including policy lookups and packet drops, which is precisely what we see in the exhibit. The traceoptions

  flag host-traffic (Answer C) is incorrect because host-traffic is typically used for traffic destined to or generated from the Junos device itself (e.g., SSH or SNMP traffic to the SRX device), not for traffic passing through the device.

  To capture flow processing details like those shown, you need the basic-datapath traceoptions flag, which provides details about packet forwarding and policy evaluation.

  Step-by-Step Configuration for Tracing (Basic-Datapath):

  Enable flow traceoptions:

  To capture detailed information about how traffic is being processed, including policy lookups and flow session creation, enable traceoptions for the flow.

  bash

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  set security flow traceoptions file flow-log

  set security flow traceoptions flag basic-datapath

  Apply the configuration and commit:

  bash

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  commit

  View the logs:

  Once enabled, you can check the trace logs for packet flows, policy lookups, and session creation details:

  bash

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  show log flow-log

  This log will contain information similar to the exhibit, including session creation attempts and packet drops due to security policy.

  Juniper Security Reference:

  Default Security Policies: Juniper SRX devices have a default security policy to deny all traffic that is not explicitly allowed by user-defined policies. This is essential for security best practices. Reference:

  Juniper Networks Documentation on Security Policies.

  Traceoptions for Debugging Flows: Using traceoptions is crucial for debugging and understanding how traffic is handled by the SRX, particularly when issues arise from policy misconfigurations or routing. Reference: Juniper Traceoptions. By

  using the basic-datapath traceoptions, you can gain insights into how the device processes traffic, including policy lookups, route lookups, and packet drops, as demonstrated in the exhibit.

• Question 38:

  Which two statements are correct about mixed mode? (Choose two.)

  A. Layer 2 and Layer 3 interfaces can use the same security zone.

  B. IRB interfaces can be used to route traffic.

  C. Layer 2 and Layer 3 interfaces can use separate security zones.

  D. IRB interfaces cannot be used to route traffic.

  Correct Answer: AB

  In mixed mode, both Layer 2 and Layer 3 interfaces can be configured to operate within the same security zone, allowing for flexible network segmentation. Additionally, Integrated Routing and Bridging (IRB) interfaces facilitate routing for

  Layer 2 bridged domains, allowing Layer 2 traffic to be forwarded at Layer 3. For more information on mixed mode and IRB functionality, refer to Juniper's Mixed Mode and IRB Documentation.

  of Answer A (Layer 2 and Layer 3 in Same Zone):

  In mixed mode configurations, it is possible to have both Layer 2 and Layer 3 interfaces within the same security zone. This allows for flexible design where different types of traffic can be handled by the same set of security policies.

  of Answer B (IRB Interfaces Can Route Traffic):

  IRB (Integrated Routing and Bridging)interfaces are used to route traffic between Layer 2 and Layer 3 domains. They can bridge traffic at Layer 2 and also provide Layer 3 routing capabilities within the same device. This allows for seamless

  interaction between Layer 2 and Layer 3 traffic in mixed mode.

  Step-by-Step Configuration:

  Configuring Layer 2 and Layer 3 in the Same Security Zone:

  Assign both Layer 2 and Layer 3 interfaces to the same security zone as follows:

  bash

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  set security zones security-zone interfaces

  Configuring IRB Interface:

  To route traffic using the IRB interface:

  bash

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  set interfaces irb unit 0 family inet address

  set security zones security-zone interfaces irb.0

  Juniper Security Reference:

  IRB Interface Overview: IRB interfaces allow for both bridging and routing functionalities, making them essential in mixed-mode environments. Layer 2 and Layer 3 in the Same Zone: This feature provides flexibility in designingnetworks that

  combine both Layer 2 switching and Layer 3 routing under the same security policies.

• Question 39:

  You are asked to configure tenant systems.

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

  A. A tenant system can have only one administrator.

  B. After successful configuration, the changes are merged into the primary database for each tenant system.

  C. Tenant systems have their own configuration database.

  D. You can commit multiple tenant systems at a time.

  Correct Answer: CD

  Each tenant system maintains its own configuration database, isolating configurations from others, enhancing security and operational efficiency. Junos OS supports multiple concurrent commit operations across tenant systems. Further

  details are covered in the Juniper Tenant System Guide.

  When configuring tenant systems on an SRX device, the following principles apply:

  Tenant Systems Have Their Own Configuration Database (Answer C): Each tenant system has its own isolated configuration database, ensuring that changes made in one tenant system do not affect others. This allows for multi-tenant

  environments where different tenants can have independent configurations.

  Commit Multiple Tenant Systems Simultaneously (Answer D): The system allows for multiple tenant systems to be committed at the same time, simplifying management when working with multiple tenants. This is particularly useful in large

  environments where multiple logical systems or tenants need updates simultaneously.

• Question 40:

  Referring to the exhibit,

  

  which two statements are correct about the NAT configuration? (Choose two.)

  A. Both the internal and the external host can initiate a session after the initial translation.

  B. Only a specific host can initiate a session to the reflexive address after the initial session.

  C. Any external host will be able to initiate a session to the reflexive address.

  D. The original destination port is used for the source port for the session.

  Correct Answer: BD

  Persistent NAT with target-host restricts session initiation to specific addresses, enhancing security. Reflexive NAT supports multiple connections by preserving the original port. Refer to Juniper NAT Configuration Documentation.

  Referring to the NAT configuration shown in the exhibit:

  Specific Host Can Initiate a Session (Answer B): The configuration uses persistent NAT with the permit target-host-port statement. This allows a specific external host (based on the target host and port used in the initial session) to initiate a

  session back to the internal host after the initial session has been established.

  Persistent NAT ensures that the translation state is maintained, allowing external hosts to connect back only under specific conditions (e.g., the same target host and port as used in the original connection). Original Destination Port (Answer

  D): The original destination port used by the internal host is retained as the source port when the session is established from outside to inside. This behavior is a result of how persistent NAT binds the internal and external sessions, ensuring

  that communication occurs over the same port used for the initial session.