CompTIA Cloud+ (CV0-004)TroubleshootingMedium
A cloud administrator is investigating an issue where users are reporting intermittent access to a critical web application hosted in a public cloud. The application has multiple instances behind a load balancer. Initial checks show that all instances are reporting as healthy. However, logs from the load balancer show frequent connection resets from some client IPs. What is the MOST likely cause of this issue?
- AInsufficient network bandwidth between the load balancer and the application instances.
- BThe application instances are experiencing high CPU utilization, leading to slow responses.
- CSecurity group or firewall rules on the application instances are blocking some client IPs.
- DThe load balancer's health checks are misconfigured, reporting unhealthy instances as healthy.
Show answer & explanationAnswer & explanation
Correct answer: C. Security group or firewall rules on the application instances are blocking some client IPs.
Frequent connection resets from specific client IPs, even with healthy instances, strongly suggests that network access control mechanisms, such as security groups or firewalls, are selectively blocking those connections.
Why the other options are wrong
- A. Insufficient bandwidth would likely affect all users or cause general slowdowns, not specific client IP connection resets.
- B. High CPU utilization would typically result in slow responses or timeouts for all users, not targeted connection resets for specific client IPs.
- D. If health checks were misconfigured, instances would likely fail to serve traffic or be marked unhealthy, not cause specific client connection resets while instances are reporting healthy.
Network ACLs/Security Groups
Virtual firewalls that control inbound and outbound traffic for network interfaces or instances in a cloud environment.
- Operate at the instance or subnet level.
- Can be stateful or stateless.
- Used to filter traffic based on IP address, port, and protocol.
Memory trick: Connect Safely, Rules Apply to Everyone