COA COA High Availability & Fault Tolerance 2 — Questions and Answers
Question 1: How many controller nodes are typically recommended as the minimum for quorum-based OpenStack HA?
- 2
- 3 (Correct answer)
- 4
- 5
Correct answer: 3
Three controller nodes are the minimum recommended for quorum, preventing split-brain scenarios in Galera and Pacemaker clusters.
Question 2: What happens to a running instance during a successful OpenStack live migration?
- The instance is stopped, moved, and restarted
- The instance continues running with minimal downtime (Correct answer)
- The instance data is deleted and recreated on the target
- The instance is snapshotted and terminated
Correct answer: The instance continues running with minimal downtime
Live migration transfers a running instance's memory and CPU state to another host while keeping the instance operational throughout the process.
Question 3: Which OpenStack alarming service evaluates metric thresholds and triggers actions for automated fault response?
- Ceilometer
- Aodh (Correct answer)
- Gnocchi
- Panko
Correct answer: Aodh
Aodh is OpenStack's alarming service that evaluates metric thresholds from Gnocchi and triggers notifications or Heat scaling actions.
Question 4: What is the purpose of a floating IP in an OpenStack high availability architecture?
- Providing internal DNS resolution for instances
- Enabling a public IP that can be reassigned to a standby instance during failover (Correct answer)
- Routing traffic between availability zones
- Encrypting inter-service API communication
Correct answer: Enabling a public IP that can be reassigned to a standby instance during failover
Floating IPs can be disassociated from a failed instance and quickly reassigned to a standby instance, maintaining external service availability.
Question 5: Which HAProxy directive configures HTTP health checks against backend OpenStack API nodes?
- balance roundrobin
- option httpchk (Correct answer)
- mode tcp
- timeout connect
Correct answer: option httpchk
The `option httpchk` directive tells HAProxy to send HTTP requests to backend OpenStack API nodes to detect unhealthy backends.
Question 6: Which OpenStack project provides DNS as a service with support for highly available DNS backends?
- Neutron
- Designate (Correct answer)
- Barbican
- Aodh
Correct answer: Designate
Designate is OpenStack's DNS-as-a-Service project that integrates with DNS backends like BIND and PowerDNS to provide zone and record management.
COA COA High Availability & Fault Tolerance 2
How many controller nodes are typically recommended as the minimum for quorum-based OpenStack HA?