JN0-335 Juniper Security, Specialist (JNCIS-SEC) Free Practice Exam Questions (2025 Updated)

The DNS ALG is an application layer gateway that handles data associated with locating and translating domain names into IP addresses. The DNS ALG supports the following features:

DDNS: The DNS ALG supports dynamic DNS (DDNS), which allows hosts to update their DNS records dynamically when their IP addresses change. The DNS ALG monitors the DDNS update messages and performs the necessary address transformations2

DNS doctoring: The DNS ALG performs DNS doctoring, which is a process of modifying the DNS responses to match the NAT address translation. This is done to resolve the problems introduced by NAT, such as the mismatch between the internal and external IP addresses of a host. The DNS ALG performs the IPv4 and IPv6 address transformations for both DNS and DDNS responses2

The DNS ALG does not support VPN tunnels or NAT itself. The DNS ALG works with NAT, but does not perform NAT. The DNS ALG only supports UDP traffic, not TCP traffic2 References:

1: Juniper Security Specialist (JNCIS-SEC) (JN0-334) | Study Guide 3

2: Junos OS Security Configuration Guide | DNS ALG 1

 The error occurred because the “http” application is not defined in this context of Juniper SRX Series device configuration. One solution is to create a custom application named “http” at the [edit applications] hierarchy level (Option C). Another solution is to modify the security policy to use the built-in “junos-http” application which is predefined and doesn’t need an explicit definition (Option D). Options A and B are not correct because they do not address the root cause of the error, which is the undefined application “http”. References: The answers can be verified from Juniper’s official documentation on security policies and applications available on their website. Here are some relevant links:

Security Policies Feature Guide for Security Devices

Understanding Applications and Application Sets for SRX Series Devices

Configuring Custom Applications for SRX Series Devices

Predefined Applications for SRX Series Devices

 AppQoE is an AppSecure component that provides application quality of experience by monitoring the network performance and dynamically adjusting the traffic routing based on predefined policies1. AppQoE can detect excessive packet loss on a WAN link and route the traffic to another link that has better performance2. AppQoE can also prioritize the traffic based on the application type and user group3. AppQoE is suitable for accomplishing the task of routing traffic from the degraded link to the working link.

The other options are not correct for the following reasons:

AppFW is an AppSecure component that provides application firewalling by enforcing granular policies to allow, deny, or limit access to applications based on user roles, locations, and devices4. AppFW does not monitor or adjust the traffic routing based on network performance.

AppQoS is an AppSecure component that provides application quality of service by allocating bandwidth and shaping traffic based on application priority and user group. AppQoS does not monitor or adjust the traffic routing based on network performance.

APBR is an AppSecure component that provides application-based routing by selecting the best path for each application based on predefined criteria such as latency, jitter, packet loss, and cost. APBR does not monitor the network performance dynamically or adjust the traffic routing automatically.

References: AppSecure Overview Understanding AppQoE Configuring AppQoE Understanding AppFW [Understanding AppQoS] [Understanding APBR]

A vSRX is a virtualized security platform that runs on various hypervisors and cloud environments. It provides firewall and NAT services, as well as other security features, such as IPS, VPN, UTM, and AppSecure. A single vSRX can fulfill the minimum requirements for providing firewall and NAT services in a private cloud, as it can be deployed as a gateway or an edge device, and can scale up or down as needed. A vSRX can also interoperate with other Juniper and third-party products, such as Contrail Networking, Junos Space Security Director, and Sky ATP. A single vSRX is more cost-effective and simpler to manage than having separate vSRX instances for firewall and NAT services. A cSRX is a containerized version of vSRX that runs on Linux-based platforms. It provides similar security features as vSRX, but with a smaller footprint and faster deployment. However, a cSRX is not yet supported on all cloud environments, and it may have some limitations compared to vSRX, such as lower throughput and fewer interfaces. Therefore, a single cSRX may not be able to fulfill the minimum requirements for providing firewall and NAT services in a private cloud, depending on the specific cloud platform and the performance and scalability needs. A cSRX for firewall services and a separate cSRX for NAT services would also introduce more complexity and overhead than a single vSRX. References: vSRX Overview, cSRX Overview, JNCIP-SEC Certification

In a Juniper Networks chassis clustering setup, when you enable chassis clustering on two devices and assign a cluster ID and a node ID to each device, the correct order for rebooting the devices is: C. Reboot the primary device, then the secondary device. Explanation: After assigning the cluster ID and node ID to each device, it is a good practice to reboot the primary device first. This ensures that the primary device comes online with the specified cluster and node IDs. Once the primary device is up and running, you can then reboot the secondary device. The secondary device will recognize the existing cluster and node IDs assigned to the primary device and join the cluster accordingly.

Juniper Secure Analytics (JSA) is a security information and event management (SIEM) system that consolidates, analyzes, and manages surveillance data from network devices, endpoints, and applications. JSA uses two types of data collectors: Event Collector and Flow Collector1

The Event Collector collects and parses logs from various log sources, such as firewalls, routers, servers, and intrusion detection or prevention systems. The Event Collector normalizes the log data into a common format and sends it to the JSA console for further analysis and correlation. The Event Collector supports different protocols for log collection, such as syslog, SNMP, JDBC, and SDEE12

The Flow Collector collects and processes network traffic data from various flow sources, such as Flowlog files, NetFlow, J-Flow, sFlow, and Packeteer. The Flow Collector enriches the flow data with additional information, such as application identification, geolocation, and threat intelligence. The Flow Collector sends the flow data to the JSA console for further analysis and correlation. The Flow Collector can use statistical sampling to reduce the amount of flow data that is collected and processed, which can improve the performance and scalability of the system12

The Event Collector does not collect information using BGP FlowSpec, which is a protocol that allows the distribution of traffic flow specification rules among BGP peers. BGP FlowSpec is not a supported flow source for JSA3

The Flow Collector does not parse logs, which are textual records of network activity generated by log sources. The Flow Collector only handles flow data, which are binary records of network traffic generated by flow sources12

References: 1: Data Collection | JSA 7.5.0 | Juniper Networks 2: Data Collection - TechLibrary - Juniper Networks 3: Understanding BGP FlowSpec - TechLibrary - Juniper Networks

SSL proxy is a feature that allows SRX Series devices to act as an intermediary between the client and the server for SSL/TLS encrypted traffic. SRX Series devices support two types of SSL proxy: SSL forward proxy and SSL reverse proxy. SSL forward proxy is also known as web proxy or client-protection, and SSL reverse proxy is also known as server-protection1.

SSL forward proxy enables the SRX Series device to decrypt the client-side traffic and apply security policies before re-encrypting and forwarding it to the server. This allows the SRX Series device to inspect the application data and identify the applications and threats in the encrypted traffic2.

SSL reverse proxy enables the SRX Series device to decrypt the server-side traffic and apply security policies before re-encrypting and forwarding it to the client. This allows the SRX Series device to protect the server from malicious clients and provide load balancing and high availability for the server3.

References:

Configuring SSL Proxy

SSL Forward Proxy Overview

SSL Reverse Proxy Overview