PCNSA Policy Evaluation and Management — 10 Questions

Question 1

An administrator needs to implement a policy where traffic from the 'Sales' zone to the 'Finance' zone is allowed only for the 'ms-office365' application, but traffic from 'Sales' to 'Finance' using any other application must be denied. Which rule design meets this requirement efficiently?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Create a rule that allows ms-office365 from Sales to Finance, and place a deny all rule after it.. In Palo Alto firewalls, security rules are either allow or deny, not both. To allow only 'ms-office365' and deny all other traffic from Sales to Finance, you create an allow rule for that application, followed by a deny-all rule for the same source/destination. This ensures efficiency by allowing the specific traffic first, then blocking everything else. Option A is incorrect as it uses a deny-all first, then tries to allow with an application default deny, which is not a valid concept and would require an explicit allow rule. Option B is incorrect because allowing all traffic and then denying the specific application defeats the purpose. Option D is invalid because a single rule cannot contain both allow and deny actions.

Answer

Create a rule that denies all traffic from Sales to Finance, and then an application default deny rule that allows ms-office365.

Answer

Create a rule that allows all traffic from Sales to Finance, then a rule that denies ms-office365.

Answer

Create one rule that allows ms-office365 and denies all other traffic from Sales to Finance.

Question 2

A security administrator is troubleshooting a policy misconfiguration. The firewall is configured with a security rule that allows traffic from the 'Engineering' zone to the 'Servers' zone. However, traffic from an Engineering user to a server in the 'DMZ' zone is being denied. What is the most likely cause?

Accepted Answer

The rule only allows traffic from Engineering to Servers zone, not DMZ.. The security rule explicitly permits traffic from the 'Engineering' zone to the 'Servers' zone. Traffic destined to the 'DMZ' zone is a different zone, so the rule does not apply. By default, Palo Alto Networks firewalls enforce a deny-all policy for any traffic that does not match an explicit allow rule, which is why the traffic is denied.

Answer

The rule is configured as an intrazone rule.

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The rule is disabled in the rulebase.

Answer

SSL decryption is blocking the traffic.

Question 3

A network engineer needs to ensure that all traffic from the 'Guest' zone to the 'Internet' zone is inspected for malware, but also wants to allow high-bandwidth video conferencing traffic to bypass threat inspection for performance reasons. Which approach best achieves this?

Accepted Answer

Create two rules: one for general traffic with 'allow' action and a 'threat' profile, and a higher-priority rule for video conferencing traffic with 'allow' action and no threat profile.. It uses two security rules with different priorities: a higher-priority rule for video conferencing traffic with an 'allow' action and no threat profile to bypass inspection, and a lower-priority rule for general traffic with an 'allow' action and a threat profile to enforce malware inspection. This leverages the firewall's rule-ordering logic, where the first matching rule is applied, allowing selective bypass of threat inspection for specific traffic while maintaining security for other traffic.

Answer

Create a single rule with 'allow' action and no security profiles, and rely on the firewall's default behavior to inspect malware.

Answer

Create a single rule with 'allow' action and a 'threat' profile applied, and rely on the firewall's ability to skip inspection for video traffic automatically.

Answer

Use policy-based forwarding to route video traffic to a separate interface that has no security profiles.

Question 4

A firewall administrator notices that a security rule intended to block traffic from a specific IP address is not working. The rule is placed at the bottom of the security rulebase, and the traffic is being allowed by a rule higher in the list. What is the most likely cause?

Accepted Answer

The rule is positioned below an allow rule that matches the same traffic.. The Palo Alto Networks firewall evaluates security rules in top-down order, from the first rule in the rulebase to the last. If a rule that allows traffic is placed higher in the list, it will match and permit the traffic before the lower-placed block rule is ever evaluated. The block rule at the bottom is effectively never reached for that traffic, which is why the intended blocking action fails.

Answer

The source IP is negated in the rule.

Answer

The rule is placed at the top of the rulebase and overridden by a later rule.

Answer

The rule is disabled in the rulebase.

Question 5

An organization has a security policy that requires all outbound HTTP traffic from the 'Corporate' zone to the 'Internet' zone to be inspected by the URL Filtering profile. However, the administrator notices that some users can still access blocked categories. What is the most likely cause?

Accepted Answer

The URL Filtering profile is set to 'alert' instead of 'block' for the relevant categories.. If the URL Filtering profile is set to 'alert' instead of 'block' for the relevant categories, the firewall will log the violation but still allow the traffic to pass. This means users can access blocked categories even though the rule is correctly applied, as the profile does not enforce a blocking action.

Answer

The firewall is configured to use DNS sinkholing, which bypasses URL filtering.

Answer

The rule is placed too low in the rulebase and a higher rule allows traffic without URL filtering.

Answer

The rule uses a source zone of 'Corporate' but the users are in a different zone.

Question 6

A firewall administrator is tasked with implementing a policy that allows SSH access from the 'Admin' zone to the 'Core' zone only for specific administrators, and all other SSH attempts should be logged and dropped. The company has a large number of administrators. Which method is most efficient and scalable?

Accepted Answer

Create a rule with source zone 'Admin', destination zone 'Core', application 'ssh', source user set to an LDAP group containing the administrators, action 'allow', and a second rule with same match criteria but action 'drop' and log at end.. It uses an LDAP group as the source user attribute, which allows dynamic membership management without manual IP updates. The first rule permits SSH for the group, and the second rule logs and drops all other SSH attempts, ensuring only authorized administrators are allowed while unauthorized attempts are recorded for auditing. This approach is scalable for a large number of administrators because it leverages user-based policies rather than IP-based rules.

Answer

Create a single rule with source zone 'Admin', destination zone 'Core', application 'ssh', source user 'any', action 'allow' and enable logging.

Answer

Create a rule with source zone 'Admin', destination zone 'Core', application 'ssh', action 'allow', and rely on the firewall's default deny rule for others.

Answer

Create a rule with source zone 'Admin', destination zone 'Core', application 'ssh', source address list of all administrators' IPs, action 'allow', and a catch-all drop rule.

Question 7

Which TWO statements correctly describe best practices for managing security policies in Palo Alto Networks firewalls? (Choose two.)

Accepted Answer

Use zone-based policies instead of IP-based policies whenever possible.. Zone-based policies reduce complexity and improve scalability by grouping interfaces into security zones, allowing policies to be applied based on traffic direction (e.g., from Trust to Untrust) rather than individual IP addresses. This aligns with Palo Alto Networks' best practice of using zones to simplify rule management and enhance security posture, as IP-based policies become unmanageable in dynamic environments.

Answer

Enable logging on all rules to ensure complete audit trails.

Answer

Sort rules alphabetically by name to simplify rulebase navigation.

Answer

Use service objects based on TCP/UDP ports to define application traffic.

Question 8

Which THREE factors should be considered when troubleshooting a 'deny' rule that is unexpectedly blocking traffic? (Choose three.)

Accepted Answer

The position of the deny rule in the rulebase relative to allow rules.. The firewall evaluates rules in top-down order, and a deny rule placed above an allow rule for the same traffic will match first and block the traffic, even if a subsequent allow rule would have permitted it. This is a fundamental aspect of policy evaluation in Palo Alto Networks firewalls, where the first matching rule is applied and no further rule processing occurs.

Answer

Whether logging is enabled on the rule.

Answer

Whether SSL decryption is enabled for the traffic.

Question 9

A user at 192.168.1.10 attempts to access a social networking site (application: social-networking). Based on the exhibit, what will the firewall do?

Accepted Answer

Deny the traffic because rule 2 matches and denies social-networking.. The firewall evaluates rules in order from top to bottom. Rule 2 explicitly denies the application 'social-networking', and since the user at 192.168.1.10 is attempting to access a social-networking site, rule 2 matches before any subsequent rule. Therefore, the traffic is denied. Option D is correct because rule 2 matches and denies the traffic.

Answer

Allow the traffic because rule 1 matches and allows all web traffic.

Answer

Allow the traffic because rule 3 allows all traffic.

Answer

Deny the traffic because no rule allows social-networking.

Question 10

A company has a Palo Alto Networks firewall in production. They recently configured a new security policy rule to allow outbound HTTPS traffic from the internal network (10.0.0.0/8) to the internet. The rule is placed after a block rule that denies all traffic from 10.0.0.0/8 to any external destination. After committing, users report that HTTPS access is still blocked. The administrator checks the firewall logs and sees that the traffic is being denied by the block rule. The administrator verifies the rule order: the new allow rule is at position 5, and the block rule is at position 3. The administrator also checks that the source zone (Trust) and destination zone (Untrust) are correct. What is the most likely cause of the issue?

Accepted Answer

The allow rule is placed below the block rule, so the block rule is evaluated first.. The Palo Alto Networks firewall evaluates security policy rules in sequential order from top to bottom. Since the block rule at position 3 is evaluated before the allow rule at position 5, traffic matching the block rule is denied immediately, and the allow rule is never reached. This is the most likely cause of the issue, as the rule order directly determines which rule is applied first.

Answer

There is a NAT policy that is interfering with the allow rule.

Answer

The allow rule has an incorrect application (e.g., ssl instead of web-browsing).

Answer

The allow rule has the wrong source address (e.g., 10.0.0.0/8 is correct).