Juniper JN0-232 Security, Associate (JNCIA-SEC) Exam Practice Test

Security policies on SRX support several actions:

Permit:Allows traffic to pass according to the rule.

Deny:Silently drops the traffic without notifying the source.

Reject:Drops the trafficand sends a TCP RST (for TCP) or ICMP unreachable (for UDP/other protocols)back to the source. This provides feedback to the sending host.

Next-policy:Allows policy chaining to evaluate the next policy set.

Therefore, the action that causes traffic to drop and a message to be sent to the source isreject.

When a packet enters an SRX interface, aroute lookupis performed:

It determines theegress interface(Option B) by checking the destination IP against the routing table.

Once the egress interface is known, its associatedegress security zone(Option D) is also determined.

Theingress interface (Option A)is already known when the packet arrives, so the route lookup does not determine it.

DNS name (Option C):DNS is unrelated to routing lookups.

Correct Results:egress interface, egress security zone

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

Security policies in Junos OS match traffic based on specific criteria:

Source and destination addresses(Option B).

Application(Option D), which may be defined as services (e.g., tcp/80) or recognized through AppID.

Other options:

MAC addresses(Option A) are not used in policy matching; policies operate at Layer 3/4.

Interface name(Option C) is used in firewall filters, not in security policy definitions.

Correct Criteria:Source address and Applications

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

Source NAT (Network Address Translation) is used on SRX devices to allow hosts with private IP addresses to access external networks, such as the Internet. The SRX translates theprivate IP address of the source host into a public IP addressbefore forwarding traffic toward the destination.

It does not translate MAC addresses (Option A).

NAT is unidirectional in this case: it specifically translates private-to-public in the outbound direction, while the reverse (return traffic) is handled automatically through the session table. It is not a bidirectional translation (Option C).

NAT processing occurs as part of the flow module, not limited only to ingress traffic (Option D).

Therefore, the correct statement is that source NAT translatesprivate IP addresses to public IP addresses.

From the exhibit:

The user attempted to access https://www.wikipedia.org.

The block page indicates:

CATEGORY: NG_Reference

REASON: BY_PRE_DEFINED

The header states:“Juniper Web Filtering has been set to block this site.”

Analysis of options:

Option A:Correct. The log shows “REASON: BY_PRE_DEFINED,” which means the site was blocked because it matched apredefined categoryin the Web filtering database.

Option B:Correct. The category “NG_Reference” indicates that theNextGen (Enhanced/Cloud-based) Web Filtering typeis being used.

Option C:Incorrect. The exhibit does not provide any information about SSL proxy configuration; it only shows that the HTTPS site was blocked.

Option D:Incorrect. The block page shown is the standard Juniper default block page, not a custom message.

Correct Statements:The URL matches a predefined Web filtering category, and the NextGen Web Filtering type is being used.

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

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.

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).

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.

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

Security Director (Option B):A Junos Space application that provides a centralized interface for managing, monitoring, and maintaining multiple SRX firewalls.

Juniper Secure Analytics (Option A):Focuses on SIEM/log analysis, not centralized firewall management.

Identity Management Service (Option C):Provides user identity integration for policy enforcement, not a management UI.

Secure Connect (Option D):A VPN client solution, not a firewall management platform.

Correct UI:Security Director

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.

Traceoptions in thesecurity flow hierarchyprovide debugging for how packets are processed in the flow module.

The correct flag to capturedetailed packet-level debuggingispacket-dump (Option A). This outputs packet-level trace messages showing flow decisions, NAT processing, and policy matches.

general (Option B):Provides basic flow trace information but not full packet inspection.

state (Option C):Tracks flow state transitions, less detailed than packet-dump.

basic-datapath (Option D):Provides high-level datapath debugging, not detailed flow troubleshooting.

Correct Flag:packet-dump

Unified security policies (USPs) provide integrated application-aware controls usingAppIDand extend traditional zone-based policy enforcement.

Option A:Correct. If traffic matches a unified security policy, it is not re-evaluated by traditional security policies. Unified policies take precedence for matched flows.

Option B:Incorrect. Traditional policies rely on Layer 3/4 attributes. Unified policies go deeper by leveraging AppID, which inspects traffic up to Layer 7.

Option C:Incorrect. Traffic matching a traditional policy is unaffected by unified policy unless unified mode is explicitly configured for those flows.

Option D:Correct. Dynamic application recognition in unified policies usesLayer 7 (application-layer) inspectionvia AppID.

Correct Statements:A and D

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

SRX devices operate on adefault deny-all policyif no explicit match is found:

If a packet does not match any configuredzone-basedorglobalpolicy, it is implicitly denied.

The traffic is discarded silently by the default security policy (Option A).

Option B:No predefined “safe zone” exists.

Option C:Logging occurs only if explicitly configured; default deny does not automatically log traffic.

Option D:Incorrect, since the firewall defaults to deny, not permit.

Correct Behavior:Traffic is discarded by the default security policy.