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Java I/O API and Securing Applications →mediumMatchingObjective-mapped

1Z0-829 Java I/O API and Securing Applications Practice Question

This 1Z0-829 practice question tests your understanding of java i/o api and securing applications. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Match each concurrency utility to its purpose.

A
CountDownLatch: A synchronization aid that allows one or more threads to wait until a set of operations being performed in other threads completes.
CountDownLatch is used for one-time synchronization where threads wait for a set of operations to finish. It cannot be reused once the count reaches zero.
B
CyclicBarrier: A synchronization aid that allows a set of threads to all wait for each other to reach a common barrier point, and can be reused.
CyclicBarrier is reusable after the barrier is tripped, making it suitable for multi-phase computations where threads wait at each phase.
C
Semaphore: A counting semaphore that maintains a set of permits for controlling access to a resource.
Semaphore controls access to a shared resource via permits. It can be used for limiting concurrent access or signaling.
D
Exchanger: A synchronization point at which two threads can exchange objects.
Exchanger allows two threads to swap data at a common rendezvous point, useful for producer-consumer patterns with two threads.
E
CyclicBarrier: A synchronization aid that allows one or more threads to wait until a set of operations completes.
Why wrong: Incorrect — this describes CountDownLatch, which is one-time use and does not automatically reset. CyclicBarrier is reusable and requires all threads to arrive.
F
Semaphore: A synchronization aid that allows a set of threads to all wait for each other to reach a common barrier point.
Why wrong: Incorrect — this describes CyclicBarrier. Semaphore controls access via permits, not thread rendezvous.

Full breakdown with real-world context →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

CountDownLatch: A synchronization aid that allows one or more threads to wait until a set of operations being performed in other threads completes.

This question tests understanding of common concurrency utilities in java.util.concurrent such as CountDownLatch, CyclicBarrier, Semaphore, and Exchanger. A common mistake is confusing CountDownLatch (one-time use) with CyclicBarrier (reusable) and mixing up Semaphore's permit-based control with barrier synchronization.

Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✓
CountDownLatch: A synchronization aid that allows one or more threads to wait until a set of operations being performed in other threads completes.
Why this is correct
CountDownLatch is used for one-time synchronization where threads wait for a set of operations to finish. It cannot be reused once the count reaches zero.
Related concept
Standard ACLs match source addresses.
✓
CyclicBarrier: A synchronization aid that allows a set of threads to all wait for each other to reach a common barrier point, and can be reused.
Why this is correct
CyclicBarrier is reusable after the barrier is tripped, making it suitable for multi-phase computations where threads wait at each phase.
Related concept
Standard ACLs match source addresses.
✓
Semaphore: A counting semaphore that maintains a set of permits for controlling access to a resource.
Why this is correct
Semaphore controls access to a shared resource via permits. It can be used for limiting concurrent access or signaling.
Related concept
Standard ACLs match source addresses.
✓
Exchanger: A synchronization point at which two threads can exchange objects.
Why this is correct
Exchanger allows two threads to swap data at a common rendezvous point, useful for producer-consumer patterns with two threads.
Related concept
Standard ACLs match source addresses.
✗
CyclicBarrier: A synchronization aid that allows one or more threads to wait until a set of operations completes.
Why it's wrong here
Incorrect — this describes CountDownLatch, which is one-time use and does not automatically reset. CyclicBarrier is reusable and requires all threads to arrive.
✗
Semaphore: A synchronization aid that allows a set of threads to all wait for each other to reach a common barrier point.
Why it's wrong here
Incorrect — this describes CyclicBarrier. Semaphore controls access via permits, not thread rendezvous.

Common exam traps

Common exam trap: ACLs stop at the first match

ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.

Detailed technical explanation

How to think about this question

ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.

KKey Concepts to Remember

Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.

TExam Day Tips

Check inbound versus outbound direction.
Read the ACL from top to bottom.
Look for a broader permit or deny above the intended line.

Key takeaway

ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.

Real-world example

How this comes up in practice

A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.

What to study next

Got this wrong? Here's your next step.

Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related 1Z0-829 ACL questions on filtering logic and placement.

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FAQ

Questions learners often ask

What does this 1Z0-829 question test?

Java I/O API and Securing Applications — This question tests Java I/O API and Securing Applications — Standard ACLs match source addresses..

What is the correct answer to this question?

The correct answer is: CountDownLatch: A synchronization aid that allows one or more threads to wait until a set of operations being performed in other threads completes. — This question tests understanding of common concurrency utilities in java.util.concurrent such as CountDownLatch, CyclicBarrier, Semaphore, and Exchanger. A common mistake is confusing CountDownLatch (one-time use) with CyclicBarrier (reusable) and mixing up Semaphore's permit-based control with barrier synchronization.

What should I do if I get this 1Z0-829 question wrong?

What is the key concept behind this question?

Standard ACLs match source addresses.

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