Adaface Sample Backend Questions

You are working on a large-scale, distributed, and fault-tolerant message processing system designed to handle high throughput and low latency requirements. The system is based on the publish-subscribe pattern and uses multiple brokers to distribute messages across various topics and partitions. In this architecture, both publishers and subscribers are considered clients. The brokers are responsible for replicating messages among themselves to ensure fault tolerance and data durability.

A client reports successfully publishing a message on a specific topic. However, one of the subscribers has not received the message. To investigate the issue, you have gathered detailed logs and system design data, as shown below:

Based on the information provided, which of the following is the most likely reason for the issue?
            
            A: The message was not published on the topic
            B: Client C is not subscribed to the correct topic
            C: There is a replication lag between brokers B1 and B2
            D: Client C is consuming from the wrong broker
            E: The message processing system failed to acknowledge the message

A backend service is experiencing intermittent latency spikes while processing incoming requests. The service is deployed in a multi-node environment with a load balancer in front. You suspect that the issue might be related to resource contention. You collect the following performance metrics from the affected nodes during a spike:

Which of the following is the most probable cause of the latency spikes?
            A: High memory usage on the affected nodes.
            B: Disk I/O bottlenecks on the affected nodes.
            C: Insufficient CPU resources on the affected nodes.
            D: Uneven distribution of incoming requests by the load balancer.
            E: Network latency between the load balancer and the backend nodes.