CV0-004 Troubleshooting Practice Test 3 — 15 Questions

Question 1

A company is deploying a critical application in the cloud and needs to ensure that it can automatically recover from an intent—a failure of an entire cloud provider region. Which of the following architectures should be implemented?

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

Accepted Answer

Active-passive deployment across two regions with DNS-based failover. To survive a full region failure, the architecture must span at least two regions. An active-passive deployment across two regions with DNS-based failover (e.g., Route 53 health checks and failover routing) ensures that if the primary region becomes unavailable, traffic is redirected to the standby region. This is the minimum viable multi-region DR architecture for region-level intent.

Answer

Active-passive deployment across multiple availability zones in the same region

Answer

Single-region deployment with auto-scaling groups

Answer

Active-active deployment across multiple availability zones in the same region

Question 2

A cloud architect is designing a highly available web application. Which THREE of the following components should be configured in at least two availability zones? (Choose THREE.)

Accepted Answer

Web server instances. Option A (Web server instances) is correct because running compute instances across at least two Availability Zones ensures the application tier survives an AZ outage and can continue serving traffic via the load balancer. Option B (Application load balancer) is correct because an ALB must have nodes/subnets enabled in multiple AZs so it can route requests to healthy targets even if one AZ fails, providing fault tolerance at the entry point. Option C (Database instance with primary and standby) is correct because a Multi-AZ deployment keeps a synchronous standby in a second AZ, enabling automatic failover and data durability if the primary AZ goes down. Option D (DNS service such as Route 53) is not correct here because Route 53 is a globally distributed, highly available managed service that does not require the architect to configure it across multiple AZs. Option E (Auto-scaling group) is not correct because an ASG is a logical grouping that spans subnets/AZs by design; the AZ redundancy comes from the instances and subnets it launches into, not from configuring the ASG itself in two AZs.

Answer

DNS service (e.g., Route 53)

Answer

Auto-scaling group

Question 3

A cloud administrator is starting the nginx web server on a new cloud VM but it fails. According to the exhibit, what is the most likely cause of the failure?

Accepted Answer

Another service is already listening on port 80. The error 'bind() to 0.0.0.0:80 failed (98: Address already in use)' indicates that port 80 is already occupied by another process. Option A is correct. Option B is wrong because SELinux would give a permission denied error, not address in use. Option C is wrong because the error says address in use, not file not found. Option D is wrong because the error is about binding, not about configuration syntax.

Answer

The VM does not have network connectivity

Answer

SELinux is blocking nginx from binding to the port

Answer

The nginx configuration file has a syntax error

Question 4

A cloud administrator is troubleshooting why web-server-01 is not receiving traffic from an internet-facing load balancer. The load balancer is in the same VPC and subnet. According to the exhibit, what is the most likely reason?

Accepted Answer

The security group attached to the instance does not allow traffic from the load balancer. In AWS, a load balancer forwards traffic to targets, but the target's security group must explicitly allow inbound traffic from the load balancer's security group (or from the load balancer's subnet CIDR). If the security group on web-server-01 does not permit traffic from the load balancer, the health checks and client traffic will be blocked, which is the most likely cause given the instance is in the same VPC and subnet.

Answer

The instance is in a stopped state

Answer

The instance is not in the same VPC as the load balancer

Answer

The instance does not have a public IP address

Question 5

An administrator notices that a cloud-hosted database is experiencing high latency during peak usage. The CPU and memory utilization on the DB server are below 50%, but disk IOPS are consistently at the provisioned limit. What should the administrator check first?

Accepted Answer

Check if the storage volume has an IOPS cap.. The symptom pattern — low CPU/memory but disk IOPS pinned at the provisioned limit — points directly to a storage IOPS ceiling. The administrator should first confirm whether the volume is capped (e.g., gp2/gp3 baseline IOPS, io1/io2 provisioned IOPS, or a cloud provider's disk tier limit). If IOPS is the bottleneck, the fix is to increase provisioned IOPS or change volume type, not to add CPU or network.

Answer

Check network bandwidth between the DB and application servers.

Answer

Add additional storage volumes and stripe data.

Answer

Increase the number of vCPUs on the DB server.

Question 6

A hybrid cloud setup uses a site-to-site VPN between on-premises and a public cloud. Users report intermittent connectivity failures. Traceroutes show packets dropping after a specific hop. What is the most likely cause?

Accepted Answer

The MTU setting on the VPN endpoint is too low, causing packet fragmentation.. Intermittent connectivity failures with traceroute drops after a specific hop in a site-to-site VPN commonly point to an MTU mismatch. When the VPN endpoint's MTU is set too low (or the tunnel overhead isn't accounted for), large packets get fragmented or dropped, causing intermittent failures that affect some traffic but not all. The classic symptom is that small packets (ping, DNS) succeed while large packets (TLS handshakes, file transfers) fail.

Answer

The routing tables on the cloud side are missing routes for the on-premises network.

Answer

The VPN tunnel is misconfigured with incorrect pre-shared keys.

Answer

The VPN gateway is overloaded due to too many tunnels.

Question 7

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

Accepted Answer

Insufficient memory allocation. Option B (Insufficient memory allocation) is correct because when a VM's configured RAM is too low for its workload, the guest OS must page to disk or the hypervisor must balloon/swap memory, causing severe performance degradation. Option E (High CPU ready time) is correct because CPU ready time measures the percentage of time a vCPU is ready to run but waiting for a physical core, and elevated values directly indicate CPU contention and degraded VM performance. Misconfigured security groups (A) primarily affect network reachability, not steady-state performance, so they are not a common cause of degradation. Incorrect DNS settings (D) cause name-resolution failures rather than performance slowdowns. Network latency to storage (C) can affect performance, but it is not one of the two options marked correct here.

Answer

Misconfigured security groups

Answer

Network latency to storage

Answer

Incorrect DNS settings

Question 8

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.. Option A is correct because the VM console log (serial console output) captures bootloader and kernel messages, which is the primary way to see why a cloud instance fails to boot, especially when there is no network access to the guest. Option C is correct because an incorrect boot order (for example, the VM attempting to boot from a network or CD-ROM device instead of the OS disk) will prevent the operating system from starting, so verifying the boot order configuration is a standard troubleshooting step. Option B is not the best choice because if the root disk were detached, the VM would typically fail to find any bootable device, and this is usually already reflected in the console log or boot order check rather than being a separate primary step. Option D is inappropriate because rebooting the hypervisor host is disruptive to all VMs on that host and does not address a single VM's boot failure. Option E is not a troubleshooting step; deleting and recreating the VM destroys the instance and its data without diagnosing the root cause.

Answer

Verify the root disk is attached.

Answer

Reboot the hypervisor host.

Answer

Delete and recreate the VM instantly.

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. A KVM guest enters the paused state when the hypervisor cannot complete I/O to the VM's virtual disk — typically due to a storage backend failure, a full datastore, or an unreachable iSCSI/NFS target. The hypervisor pauses the VM to prevent filesystem corruption from unacknowledged writes, making a storage I/O error the most likely cause.

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.. The symptoms—high CPU ready times on web servers, increased network latency on application servers, and high await times on Ceph storage—point to resource contention across compute, network, and storage. The best first step is to review hypervisor CPU and memory allocation ratios and adjust overcommitment settings, as overcommitment can cause CPU ready time and memory swapping, leading to performance degradation. This addresses the root cause of contention rather than treating symptoms.

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 is experiencing high latency in their cloud-based database. The database is provisioned with SSD storage. Which THREE factors should the administrator investigate? (Choose three.)

Accepted Answer

Network bandwidth between application and database. Option A (Network bandwidth between application and database) is correct because insufficient throughput or a saturated link between the app tier and the DB causes round-trip delays that manifest as high query latency, so the administrator should check bandwidth utilization and any throttling. Option B (Database query optimization) is correct because poorly written queries, missing indexes, or full table scans force excessive I/O and CPU work even on SSD-backed instances, directly inflating response times. Option D (Storage IOPS limits) is correct because SSD volumes have provisioned IOPS ceilings (e.g., gp3 baseline 3,000 IOPS, io2 up to 256,000), and hitting that cap queues I/O requests and raises latency regardless of the SSD media. Option C (Number of database replicas) does not belong because replicas primarily serve read scaling and availability, not the latency of a single provisioned database's request path. Option E (Region latency) does not belong because region-level latency is a fixed geographic propagation delay and is not a tunable factor the administrator would investigate for an already-deployed database experiencing latency.

Answer

Number of database replicas

Answer

Region latency

Question 14

A cloud administrator is responsible for a multi-tier application hosted in a public cloud. The application consists of a web tier, application tier, and database tier. Recently, users have reported that the application is responding slowly during peak hours. The administrator checks the cloud monitoring dashboard and notices that the web tier instances are running at 90% CPU utilization, but the auto-scaling group has not triggered any scaling events. The scaling policy is set to scale out when average CPU exceeds 80% for 5 minutes. What should the administrator do to resolve this issue?

Accepted Answer

Review the cooldown period settings of the auto-scaling group. The cooldown period settings determine how long the auto-scaling group waits before initiating another scaling activity after a previous scaling event. If the cooldown period is too long, new scaling events may be suppressed even when the CPU threshold is exceeded for the required duration. The administrator should review and potentially reduce the cooldown period to allow the auto-scaling group to respond more quickly to high CPU utilization. Option A is wrong because manual scaling is a temporary workaround and does not address the underlying auto-scaling configuration issue. Option B is wrong because increasing the CPU threshold to 95% would make scaling less sensitive, likely worsening performance during peak hours. Option D is wrong because health check configuration affects load balancer traffic routing, not the triggering of scaling events based on CPU metrics.

Answer

Manually increase the number of web tier instances

Answer

Increase the CPU threshold to 95% to avoid unnecessary scaling

Answer

Check the health check configuration of the load balancer

Question 15

An organization is using a hybrid cloud model with an on-premises data center connected to a public cloud via a dedicated Direct Connect circuit. Users on the corporate network report that access to cloud resources is intermittently failing. The cloud administrator pings the cloud gateway and sees packet loss. The on-premises network team confirms no issues on their side. The administrator reviews the cloud provider's status page and finds no outages. What should the administrator do next?

Accepted Answer

Check the bandwidth utilization on the Direct Connect circuit. The administrator should check bandwidth utilization on the Direct Connect circuit because intermittent packet loss to the cloud gateway, with no on-premises issues and no provider outages, strongly suggests the dedicated circuit is saturated or experiencing congestion. Direct Connect circuits have finite bandwidth, and when utilization approaches capacity, packets are dropped, causing intermittent failures. Checking utilization is the logical next diagnostic step before escalating or failing over.

Answer

Submit a support ticket to the cloud provider

Answer

Reboot the on-premises router

Answer

Failover to a backup VPN connection