JN0-232 Security, Associate (JNCIA-SEC) Questions and Answers

Option B:Correct. Interfaces in the same security zone must belong to the same routing instance; zones cannot span multiple routing instances.

Option D:Correct. A security zone can contain multiple interfaces, allowing grouping of similar trust levels (e.g., multiple LAN subnets in a trust zone).

Option A:Incorrect. An interface can belong to only one zone at a time.

Option C:Incorrect. Interfaces within the same zone cannot be split across routing instances.

Correct Statements:Interfaces in the same zone must share the same routing instance, and a zone can contain multiple interfaces.

Functional zones(e.g., junos-host, management, null) are not used for forwarding transit traffic. They are used to manage traffic destined to or from the SRX device itself.

Option A:Correct. If traffic enters through a functional zone interface, it is meant for the SRX, not for transit, so it cannot exit another interface.

Option D:Correct. Transit interfaces handle forwarding traffic, but they cannot send that traffic out through a functional zone interface.

Option B and C:Incorrect, because functional zones are strictly control-plane, not transit forwarding zones.

Correct Statements:A and D

The SRX Series devices support third-party antivirus scanning engines such asAvira. To use the Avira antivirus engine, administrators must explicitly enable the engine and ensure that the required components are properly loaded.

Enable in configuration mode:

The Avira antivirus engine must be enabled under UTM configuration mode. This step ensures the SRX device uses the Avira scanning engine for antivirus inspection.

Example:

set security utm feature-profile anti-virus avira-engine enable

Reboot the SRX device:

A system reboot is required after enabling the Avira engine to load the Avira antivirus components into memory.

Without a reboot, the Avira engine will not become active.

Why not the others?

Restarting themgdprocess (Option A) only reloads the management daemon and does not load antivirus engines.

Enabling inoperational mode(Option B) is not supported; the configuration must be applied in configuration mode.

Therefore, the correct actions to use Avira Antivirus are:Enable the Avira engine in configuration mode (Option D) and reboot the SRX device (Option C).

Content filtering on SRX devices inspects and controls specific file types transferred across certain application protocols:

SMTP (Option A):Supported. Content filtering can block specific file attachments in emails.

HTTP (Option D):Supported. Content filtering can block downloads of specific file types over web traffic.

SNMP (Option B):Not supported; SNMP is a management protocol, not a content delivery protocol.

TFTP (Option C):Not supported by content filtering.

Correct Protocols:SMTP and HTTP

In Juniper SRX flow-based packet processing, theflow moduleis responsible for security functions such as screening, session management, NAT, and policy enforcement. The processing order is critical:

Screens are applied before any session lookup.This ensures that packets are inspected for anomalies, floods, or protocol violations before consuming resources for session management. Examples of these screens include TCP SYN flood protection, ICMP flood protection, and port scanning protection.

After screening, thesession lookupoccurs. At this point, the firewall checks whether the packet belongs to an existing session in the session table. If a matching session is found, the packet bypasses policy evaluation and is forwarded according to the session state.

If no existing session is found, the packet continues throughroute lookup, NAT processing, and security policy evaluationbefore a new session is created.

Thus,screening occurs before the session lookup, protecting the system early in the flow process. This design ensures efficiency by dropping malicious or malformed traffic before allocating session resources.

Multiplerouting instances(such as virtual routers or VRFs) can be configured on an SRX to provide separation of routing tables. This enables:

Maintaining separation of routing information (Option B):Different departments, tenants, or customers can have their own independent routing domains for security and isolation.

SNMP monitoring (Option A) is unrelated to routing instances.

Routing protocols (Option C) can be run inside each instance, but the purpose of multiple instances is separation, not general routing protocol management.

Simplifying interface configuration (Option D) is not a function of routing instances.

Correct Purpose:To maintain separation of routing information for security purposes.

The antivirus feature on SRX relies on signature definition files that must be regularly updated. To check the status of these updates, the correct operational command is:

show security utm anti-virus status(Option D). This displays details such as:

Antivirus engine status

Last update time of virus definitions

Version of the signature database

Other options:

Content-filtering statistics (Option A) shows counters for file-type filtering, not antivirus updates.

Anti-spam status (Option B) shows spam filtering engine connectivity.

Web filtering status (Option C) shows SBL/web filter server connection details.

Correct Command:show security utm anti-virus status

When troubleshooting packet handling on an SRX Series device, administrators need to understand exactly how theflow moduleis processing traffic. The most effective tool for this is theflow traceoptions feature.

Flow traceoptions:Provides detailed per-packet trace information showing each processing step within the flow module. It reveals how traffic is evaluated against session tables, NAT rules, and security policies. This is the recommended method for in-depth troubleshooting.

Why not the others?

Theflow session table(Option A) shows only active sessions and counters, not detailed step-by-step handling.

Theforwarding table(Option B) relates to routing and forwarding decisions, not flow security processing.

Firewall filters(Option D) can match and log traffic but do not display detailed flow processing steps.

Therefore, the correct method to get detailed information about flow handling is toenable flow traceoptions.

On SRX Series Firewalls, Junos OS automatically createssystem-defined zonesthat have special functions:

Null zone (Option A):A predefined discard zone. By default, all interfaces belong to the null zone until assigned to a user-defined zone. Traffic destined to the null zone is dropped.

Junos-host zone (Option B):A predefined functional zone that allows security policies to control traffic directed to the SRX device itself (management traffic, such as SSH, HTTP, SNMP).

Management zone (Option C):There is a predefinedmanagement functional zone, but it is not called "management" as a system-defined security zone.

DMZ (Option D):A DMZ zone must be explicitly created by the administrator, it is not system-defined.

Correct Zones:null, junos-host

Juniper SRX evaluatessecurity policies in order, top to bottom. The first matching policy determines the action, and no further policies are evaluated. This behavior can lead toshadowed policiesif later policies match the same conditions as earlier ones.

From the exhibit:

Policy1:Matches application junos-http and permits traffic.

Policy2:Matches application junos-https and permits traffic.

Policy3:Matches application junos-http again, but denies traffic.

Sincepolicy1already matches all HTTP traffic and permits it, traffic never reachespolicy3. This makespolicy3 shadowedbecause it has the same match condition as policy1 but is evaluated later in the list.

Other options:

Policy1 is not shadowed because it is evaluated first.

Policy2 is independent (application = HTTPS) and therefore unaffected.

Only policy3 is shadowed by policy1.

Correct Statement:Policy3 will be shadowed because it matches the same application as policy1.

License Requirement (Option B):NextGen Web Filtering (NGWF) is a licensed feature on SRX devices. Without a license, the service cannot operate.

Local vs. Cloud Lists (Option C):NGWF checkslocal block/allow lists first. If the URL does not match locally, the request is then checked against the Juniper cloud database.

Option A:Incorrect, since the cloud is only consulted if the URL is not in the local list.

Option D:Incorrect, as NGWF requires a valid subscription/license.

Correct Statements:NGWF requires a license, and it checks local lists before cloud lookup.

Adding interfaces (Option A):An interface must be assigned to a security zone before it can pass traffic. By default, interfaces are in the null zone and cannot send or receive traffic.

Exception traffic (Option B):Security zones define host-inbound-traffic settings, which determine what types of management or control-plane traffic (SSH, ICMP, SNMP) are permitted.

Routing instances (Options C and D):Security zones arespecific to a routing instanceand cannot include interfaces from multiple instances. Therefore, interfaces in the same zone cannot belong to different routing instances.

Correct Statements:A and B

The packet flow fornew trafficon SRX is processed in a defined order:

Screens (Option B, Step 1):Packets are first checked by screens for anomalies such as floods, malformed packets, or protocol violations.

Route Lookup (Step 2):The destination IP is checked in the routing table to determine the egress interface.

Zone Determination (Step 3):Once the ingress and egress interfaces are known, their associated zones are identified.

Security Policies (Step 4):With both zones determined, the packet is evaluated against the configured security policies.

Other options list incorrect sequences, either moving routing later or placing policies before zone determination, which is not possible.

Correct Processing Order:screens → routes → zones → security policies

The simplest and most direct method of verifying Web filtering effectiveness isto attempt to access permitted and blocked URLs.

Option A:Installing a local NGWF server is not required; NGWF queries Juniper’s cloud.

Option B:File extension checking applies to content filtering, not web filtering.

Option C:Examining policies shows configuration but does not verify enforcement.

Option D:Correct. Attempting to browse URLs that should be blocked or allowed confirms the Web filtering policy is effective.

Correct Method:Attempt to access permitted or blocked URLs

Transit traffic is defined as traffic that passesthroughthe SRX (not destined to the Routing Engine). To capture transit traffic:

Sampling and port mirroring (Option D)are the correct supported methods for capturing or exporting transit traffic. Sampling allows captured packets to be sent to a file or collector, while port mirroring sends a copy to a monitoring interface.

Option A:Firewall filters on an egress interface cannot directly capture packets; they can only count, accept, discard, or sample. Sampling itself is separate.

Option B:Loopback interface (lo0) is for control-plane traffic, not transit traffic.

Option C:tcpdump is not supported on SRX as a tool for capturing transit packets; the operational command monitor traffic interface is used, but sampling/port mirroring is the recommended scalable approach.

Correct Method:Sampling and port mirroring

Inbound Flow (before NAT):Source =10.20.30.40(internal private IP)Destination =203.0.113.1(public DNS server)

Outbound Flow (after NAT):Source =192.0.2.1(translated IP)Destination =203.0.113.1(unchanged)

Analysis:

Thesource IP (10.20.30.40)was translated to192.0.2.1. This indicatesSource NATwas applied →Option B is correct.

Thedestination IP changedbetween the inbound and outbound view. Inbound it was203.0.113.1, and outbound it is still203.0.113.1in appearance, but notice the reversal: the session entry shows it as the outbound "source" side. This confirmsDestination NAT translation has occurredfor return flow consistency →Option D is correct.

Option A:Incorrect. The original source IP was indeed translated.

Option C:Incorrect. The destination IP did change in the flow processing.

Correct Statements:

The original source IP address was translated to a new source IP address.

The original destination IP address was translated to a new destination IP address.