CV0-004 Troubleshooting Practice Test 6 — 15 Questions

Question 1

A cloud load balancer is not distributing traffic evenly to backend servers. All servers pass health checks. Which of the following is the most likely cause?

Accepted Answer

Session persistence is enabled and directing traffic to specific servers.. Session persistence (sticky sessions) is the most likely cause because it forces the load balancer to direct traffic from the same client to the same backend server, leading to uneven distribution. All servers passing health checks rules out health check issues (Option A and D). A server reaching its connection limit (Option B) would typically cause that server to stop accepting new connections, but health checks would likely fail, so it is less likely.

Answer

The health check interval is set too long.

Answer

One of the backend servers has reached its connection limit.

Answer

The health check path is incorrect.

Question 2

A cloud database cluster is experiencing replication lag. The primary node shows high write activity, and the replicas are on different availability zones. Which of the following is the most likely cause?

Accepted Answer

Network latency between the primary and replica zones is high.. Network latency between availability zones is a common cause of replication lag in asynchronous replication setups, especially when the primary has high write activity. Option A is incorrect because synchronous replication would cause the primary to wait for acknowledgment from replicas, leading to write slowdown rather than lag on replicas. Option C is incorrect because insufficient storage on replicas would typically cause disk-full errors, not replication lag. Option D is incorrect because vCPU over-allocation on the primary primarily affects compute performance, not the replication process which is more sensitive to network and disk I/O.

Answer

Replication is configured as synchronous.

Answer

The replica nodes have insufficient storage.

Answer

The primary node's vCPU is over-allocated.

Question 3

A cloud application returns HTTP 503 errors during high traffic. The application runs on VMs behind a load balancer. Which action is most likely to resolve the issue?

Accepted Answer

Add additional VMs to the backend pool.. Adding VMs increases the overall capacity to handle high traffic, directly addressing the 503 errors caused by overload. Option A is incorrect because restarting only one VM does not increase capacity; it might briefly disrupt service. Option B is incorrect because lowering the DNS TTL affects how clients resolve the domain, not the backend capacity. Option C is incorrect because increasing the health check interval only delays detection of unhealthy VMs, which does not prevent overload.

Answer

Restart the web server service on one VM.

Answer

Change the DNS TTL to a lower value.

Answer

Increase the health check interval on the load balancer.

Question 4

An automated snapshot of a cloud VM is failing with the error 'Quota exceeded for resource snapshots'. What is the most likely cause?

Accepted Answer

The maximum number of snapshots allowed has been reached.. The error 'Quota exceeded for resource snapshots' indicates that the number of snapshots has reached the maximum allowed by the cloud provider. Therefore, Option B is correct. Option A is incorrect because backup windows do not affect snapshot quotas. Option C is incorrect because a high retention policy may cause more snapshots to be retained, but the immediate error is about exceeding the quota, not the policy setting itself. Option D is incorrect because disk space is unrelated to the snapshot count limit.

Answer

The snapshot is being created during a backup window.

Answer

The snapshot retention policy is set too high.

Answer

The VM's disk is too full to create a snapshot.

Question 5

A cloud orchestration template fails to deploy resources with the error 'Resource limit exceeded'. The administrator has enough quota for all services. What is the most likely cause?

Accepted Answer

A specific resource type has reached its service limit.. Certain resource types have service-specific limits that are separate from the overall account quota. Even if the administrator has enough total quota, a specific resource type (e.g., virtual machines, storage accounts) may have reached its maximum allowed count. Option A is incorrect because a syntax error would cause a different error, such as parsing failure. Option C is incorrect because a corrupted image would typically result in image-related errors. Option D is incorrect because permission issues would generate an access denied error, not 'Resource limit exceeded'.

Answer

The template has a syntax error in the JSON.

Answer

The custom image used is corrupted.

Answer

The IAM role used does not have permission to create resources.

Question 6

Which TWO are common causes of virtual machine performance degradation in a cloud environment?

Accepted Answer

Insufficient memory allocation. The correct answers are B and E. Insufficient memory allocation causes the VM to use swap space, significantly degrading performance. High CPU ready time indicates that the VM is waiting for CPU resources due to contention, another common cause of performance degradation. Security groups (A) affect access control, not performance. Network latency to storage (C) can impact storage performance but is not as common as CPU/memory issues. Incorrect DNS settings (D) cause name resolution failures, not performance degradation.

Answer

Misconfigured security groups

Answer

Network latency to storage

Answer

Incorrect DNS settings

Question 7

Which TWO steps should an administrator take to troubleshoot a cloud VM that fails to boot?

Accepted Answer

Check the VM's console logs for error messages.. Console logs provide detailed error messages during the boot process, helping identify the root cause of boot failure. Option C is correct because incorrect boot order (e.g., trying to boot from a non-bootable device) can prevent the VM from starting; verifying and adjusting boot order is a standard troubleshooting step. Option B is incorrect because while verifying the root disk is attached is a basic check, it alone does not address other common boot issues (e.g., corrupted OS, incorrect boot configuration). Option D is incorrect because rebooting the hypervisor host affects multiple VMs and is not a targeted troubleshooting step for a single VM failing to boot. Option E is incorrect because deleting and recreating the VM is a drastic measure that results in data loss and should only be considered after all other troubleshooting steps have failed.

Answer

Verify the root disk is attached.

Answer

Reboot the hypervisor host.

Answer

Delete and recreate the VM instantly.

Question 8

Which THREE are common reasons why a cloud database instance may become unreachable?

Accepted Answer

Firewall rules blocking the database port. The three most common reasons a cloud database instance becomes unreachable are firewall rules blocking the database port (A), an incorrect connection string in the application (B), and the database service not being started (D). A full storage volume (C) may cause write failures but does not always result in unreachability, and hypervisor maintenance (E) typically uses live migration to avoid downtime.

Answer

Storage volume is full on the database server

Answer

Hypervisor maintenance causing VM reboot

Question 9

A KVM host has three VMs. The db-server VM is in a paused state. Which of the following is the most likely cause?

Accepted Answer

Storage I/O error on the VM disk. Storage I/O errors on the VM disk can cause the hypervisor to pause the VM to prevent data corruption. CPU overcommitment (Option B) typically leads to performance degradation, not pausing. Insufficient memory (Option C) can cause swapping or OOM, but not directly pausing. A network interface being down (Option D) would affect connectivity, not cause the VM to enter a paused state.

Answer

CPU overcommitment on the host

Answer

Insufficient memory on the host

Answer

Network interface is down

Question 10

A cloud instance fails to initialize. The cloud-init log shows the error above. Which of the following is the most likely cause?

Accepted Answer

The launch template specifies a block device mapping that is not attached to the instance.. The error 'No such device' indicates that the device specified in the block device mapping does not exist on the instance. Option D is correct because the launch template likely references a block device mapping for a device that is not actually attached (e.g., an ephemeral disk or misconfigured EBS volume). Option A is incorrect because an unformatted filesystem would produce a different error (e.g., 'mount: unknown filesystem type'). Option B is incorrect because if the disk were not attached at all, the device path would not appear in the system, but the error references a specific device path that is missing. Option C is incorrect because a corrupted partition table would yield errors like 'invalid partition table', not 'No such device'.

Answer

The filesystem on /dev/xvdb1 is not formatted with a recognized filesystem.

Answer

The disk is not attached to the instance at all.

Answer

The partition table on /dev/xvdb1 is corrupted.

Question 11

A company runs a critical e-commerce application on a private cloud using OpenStack. The application consists of web servers, application servers, and a MySQL database running on separate VMs. Recently, users have reported intermittent 502 Bad Gateway errors during peak hours. The operations team notices that the web server VMs show high CPU ready times and the application server VMs have increased network latency. Storage performance also shows high await times on the SSD-based Ceph cluster. The team suspects resource contention. Which of the following is the BEST course of action to diagnose and resolve the issue?

Accepted Answer

Review the hypervisor's CPU and memory allocation ratios and adjust overcommitment settings.. High CPU ready times and overall contention indicate overcommitment on the hypervisors. Adjusting overcommitment ratios can reduce contention across CPU, memory, and storage. Option A is incorrect because migrating VMs to a different host is a temporary workaround that does not address the root cause of overcommitment. Option B is incorrect because adding more vCPUs can worsen contention by increasing scheduling overhead. Option C is incorrect because QoS policies on storage only address storage contention and do not resolve CPU or network issues.

Answer

Migrate the web server VMs to a different compute host using live migration.

Answer

Increase the number of vCPUs for each web server VM to reduce CPU ready time.

Answer

Implement quality of service (QoS) policies on the Ceph cluster to guarantee IOPS for the database.

Question 12

A cloud administrator is troubleshooting a performance issue where a web application experiences intermittent slowdowns. The application is deployed on a public cloud IaaS with auto-scaling. What should the administrator check first?

Accepted Answer

Verify load balancer configuration. A misconfigured load balancer can cause uneven traffic distribution, leading to intermittent slowdowns. Option B is wrong because CPU utilization spikes might be a symptom, not the root cause, and auto-scaling should handle it. Option C is wrong because database queries are a deeper layer to investigate after network and application tiers. Option D is wrong because network latency is less likely to be intermittent.

Answer

Check CPU utilization of all instances

Answer

Analyze database query performance

Answer

Review network latency between tiers

Question 13

A company migrated to a hybrid cloud and users report slow access to files stored in the cloud. The on-premises network is 100 Mbps. What troubleshooting step should be taken?

Accepted Answer

Check VPN bandwidth and latency. Slow file access over a hybrid connection is often due to limited VPN bandwidth or high latency. Option A is wrong because increasing storage performance tier may not address network bottlenecks. Option C is wrong because moving files back defeats the hybrid cloud purpose. Option D is wrong because compression may help but isn't the first step to diagnose the issue.

Answer

Enable compression on the cloud storage gateway

Answer

Increase cloud storage performance tier

Answer

Move files to on-premises storage

Question 14

After deploying a new application version, users get 503 errors. The application runs on Kubernetes in a private cloud. What is the most likely cause?

Accepted Answer

Application health check failing. 503 errors typically indicate that the application is not passing health checks, causing the load balancer or Kubernetes service to stop routing traffic to the affected pods. Option B is incorrect because an incorrect ingress configuration usually results in 404 errors or connection timeouts, not 503. Option C is incorrect because insufficient pod resources lead to OOM kills or CPU throttling, which may cause 503s only indirectly if health checks fail, but the more direct cause is failed health checks. Option D is incorrect because node port exhaustion is rare and would cause connection refused, not 503.

Answer

Incorrect ingress configuration

Answer

Insufficient pod resources

Answer

Node port exhaustion

Question 15

A cloud administrator is troubleshooting a connectivity issue between two VPCs in the same region. Which TWO actions should the administrator verify? (Choose two.)

Accepted Answer

VPC peering connection status. The correct answers are A and B. The VPC peering connection must be in the 'active' state (A), and the route tables in both VPCs must have routes pointing to the peering connection (B). Security group rules (C) are not the primary check because security groups are stateful and allow return traffic by default; they can be configured to block traffic but are not the first thing to verify in this scenario. VPN tunnel configuration (D) is a different connectivity method. Internet gateway attachment (E) is for internet access, not VPC peering.

Answer

Security group rules

Answer

VPN tunnel configuration

Answer

Internet gateway attachment