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

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

Themanagement functional zoneon SRX devices is a special predefined zone with unique characteristics:

It isautomatically created(Option C) and cannot be deleted.

It is used specifically formanagement-related traffic(Option A), such as SSH, Telnet, web management (J-Web), SNMP, and other control-plane services.

It does not contain revenue (data) interfaces (Option B is incorrect). Interfaces must be explicitly configured into user-defined zones.

The management zone can be referenced in policies if inter-zone communication involving management traffic is needed (Option D is incorrect).

Correct Statements:A and C

Transit traffic is defined as traffic passingthrough the SRX firewall(from one interface/zone to another). To allow transit traffic:

Interfaces must be placed into auser-defined security zone(Option C).

Policies between zones are then applied to control traffic.

Thenull zone (Option A)discards all traffic.

TheJunos-host zone (Option B)is used for traffic destined to the SRX itself, not transit.

Functional zones (Option D)are predefined and used for special purposes (like management), not for transit traffic.

Correct Configuration:User-defined security zone

Global security policies extend the flexibility of policy enforcement across the SRX. They are not tied to specific source and destination zones:

From-zone and to-zone contexts are not required(Option A). Global policies apply across all zones unless restricted by match conditions.

Global security policies do not require specific zone contexts(Option B is incorrect).

Global policies areprocessed after zone-based policies, not before. This means that zone-based security policies take precedence (Option C is incorrect).

Administrators can configure bothzone-based security policies and global security policies at the same timeon the same device (Option D is correct).

This allows flexible designs where specific policies can be enforced by zone, while general policies can be applied globally without duplicating rules across multiple zones.

Exception traffic refers to traffic that must be sent from thePacket Forwarding Engine (PFE) to the Routing Engine (RE)for processing, such as routing protocol updates, management traffic, and control-plane destined packets.

Option B:Correct. Exception traffic is rate-limited on the internal connection between the PFE and RE to protect the Routing Engine from denial-of-service attacks.

Option A:Incorrect. Exception traffic is not handled only on the PFE; it requires RE involvement.

Option C:Incorrect. Rejected traffic by security policies is simply dropped, not classified as exception traffic.

Option D:Incorrect. Malformed packets are dropped, not considered exception traffic.

Correct Statement:Exception traffic is rate-limited between the PFE and RE.

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

Static NAT:Provides a one-to-one bidirectional mapping between internal and external IP addresses. When configured, the translation automatically applies in both directions (Option A is correct). It does not use Port Address Translation (Option C is incorrect).

Destination NAT:Allows external clients to access internal resources by translating the destination address. It supportsport forwardingso specific services (e.g., HTTP on port 80) can be forwarded to an internal host (Option D is correct). It does not require equal-sized address ranges (Option B is incorrect).

Correct Characteristics:Static NAT is bidirectional, and Destination NAT supports port forwarding.

PAT (Port Address Translation), also called NAT overload, allows many devices to share a single public IP:

Option C:Correct. Multiple internal hosts share a single external IP.

Option D:Correct. Each internal host is mapped to the same public IP but differentiated by unique port numbers.

Option A:This describes basic static NAT (1-to-1 mapping).

Option B:Incorrect, this describes general NAT behavior but not specific to PAT.

Correct Statements:PAT enables multiple internal devices to share one external IP, and it maps internal IPs to external IP + port.

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.

From the exhibit configuration:

[edit security policies from-zone Trust to-zone Trust]

policy allow-all {

match {

source-address any;

destination-address any;

application any;

}

then {

permit;

}

}

Thefrom-zoneandto-zoneare both set toTrust → Trust.

This means the policy is governing trafficwithin the same zone.

Policies within the same zone are calledintra-zone policies.

Analysis of options:

Global policy (A):Applied universally across zones, not zone-specific. Not the case here.

Inter-zone policy (B):Applies between twodifferentzones (e.g., Trust → Untrust). Not the case here since both zones are Trust.

Intra-zone policy (C):Correct. Applies to traffic within the same zone (Trust → Trust).

Default policy (D):The implicit deny-all policy that applies when no policy matches. Not shown in this exhibit.

Correct Policy Type:Intra-zone policy

Destination NAT purpose (Option C):Used to allow external hosts on the Internet to access internal/private resources (such as a web server in the DMZ). Destination NAT changes the destination IP of incoming traffic to match the internal server.

Pool-based NAT (Option D):SRX supports destination NAT pools, allowing multiple public IP addresses or ranges to be translated to internal servers.

Incorrect options:

Option A describessource NAT, not destination NAT.

Option B is incorrect because SRX does not support “interface-based” destination NAT.

Correct Statements:C and D

Exception traffic is traffic that must be sent from the Packet Forwarding Engine (PFE) to the Routing Engine (RE) for processing, such as routing protocol updates, management traffic, or other control-plane packets. Because the RE is a limited and critical resource, Junos OS implementsrate limiting on exception traffic.

The purpose is toprevent denial-of-service (DoS) attacks on the Routing Engineby controlling the amount of traffic directed to it.

This ensures the RE continues to process control-plane operations reliably, even under potential attack or heavy traffic conditions.

Rate limiting does not enhance forwarding plane performance (Option A), simplify interface configuration (Option B), or manage routing protocols directly (Option D).

From the exhibit:

The internal host (172.25.11.101) is located in theTrust zone.

The external address (203.0.113.199/30) is used for communication with the ISP.

The requirement is thatsessions can only be initiated from the external device(the ISP or untrust side) toward the internal host.

This requirement matches the behavior ofDestination NAT:

Destination NAT only (Option A):Maps the external/public IP (203.0.113.199) to the internal/private IP (172.25.11.101). This allows inbound connections to be translated and sent to the internal host. The internal host cannot initiate outbound sessions, since the translation only applies to inbound traffic.

Source NAT only (Option B):Used for outbound sessions from internal private IPs to the Internet. This does not meet the requirement.

Static PAT (Option C):Maps a single port of a public IP to a private IP/port. The exhibit does not indicate a port-based translation.

Static NAT and source NAT (Option D):Would provide bidirectional communication, allowing sessions to be initiated in both directions. This contradicts the requirement.

Correct NAT Type:Destination NAT only

For an SRX firewall interface to respond to management traffic such as ICMP pings:

Theinterface must be assigned to a security zone(Option A). If an interface is not part of any zone, it is placed into the null zone, which drops all traffic.

Additionally, the zone must be configured to allow management traffic types ashost-inbound-traffic(Option D). For ICMP, the protocol must be explicitly allowed under host-inbound-traffic for that zone.

Other options:

Security policies (Option B) control traffic traversing the firewall, not traffic destined to the SRX device itself.

Assigning the interface to the null zone (Option C) prevents any communication, including management.

Correct Actions:Assign the interface to a zone and configure ICMP under host-inbound-traffic.

By default, SRX 300 Series Firewalls come with predefined security policies:

Trust-to-Untrust (Option B):A default policy exists to permit all traffic from thetrust zone to the untrust zone.

Trust-to-Trust (Option D):Intra-zone traffic is permitted by default; hence, a trust-to-trust policy is installed automatically.

Untrust-to-Trust (Option A):Not allowed by default, since external traffic must be explicitly permitted by an administrator.

Management-to-Trust (Option C):No such default policy exists.

Correct Policies:Trust-to-Untrust and Trust-to-Trust

Routing instances:Security zones are local to their routing instance. Theycannot be shared between routing instances(Option B is correct). Each routing instance must define its own zones.

Intrazone and interzone traffic:Both types of traffic require policies in Junos OS. Intrazone traffic must have an explicit intra-zone policy to be controlled (Option C is correct).

Sharing zones:Option A is incorrect, as zones cannot span routing instances.

Multiple zones:SRX devices fully support multiple security zones (trust, untrust, DMZ, etc.). Option D is incorrect.

Correct Statements:B and C