Free Practice Questions for Juniper JN0-232 Exam

When source NAT uses a pool of addresses from thesame subnet as the egress interface, the firewall must respond to ARP requests for those NAT pool IPs. Without this, upstream devices would not know how to forward traffic destined for those IPs.

Proxy ARPis required (Option D). It enables the SRX to answer ARP requests on behalf of the NAT pool addresses.

Static NAT (Option A)is unrelated and maps one-to-one, not required here.

Dynamic DNS (Option B)has no relation to NAT pools.

Destination NAT (Option C)applies to inbound translations, not outbound source NAT pools.

Correct Feature:Proxy ARP

SSH Access (Option B):Host-inbound-traffic controls traffic destined to the SRX device itself (management/control plane). If host-inbound-traffic is not configured to allow SSH, then SSH access to the firewall is blocked.

Explicit Zone Configuration (Option D):For user-defined security zones, host-inbound-traffic must be explicitly configured to allow specific services (SSH, ICMP, SNMP, etc.).

Console Access (Option A):Console access is not controlled by host-inbound-traffic. Console access is always available directly.

Management Zone (Option C):In the management functional zone, host-inbound-traffic is implicitly allowed for management services, so this is not explicitly required.

Correct Statements:B and 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

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

Screen options are used to detect and prevent attacks such as floods, scans, and malformed packets. In some cases,false positivesmay occur, where legitimate traffic is mistakenly identified as malicious.

To address this, administrators can configure thealarm-without-dropoption (Option D). This setting generates alarms/logs for suspicious traffic without actually dropping it, allowing verification before taking further action.

Enabling all screen options (Option A) may increase false positives further.

Discarding traffic immediately (Option B) risks disrupting legitimate communication.

Increasing sensitivity (Option C) worsens the problem, since false positives would increase.

Correct Action:Use alarm-without-drop to log the traffic without dropping it.

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.

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

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

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