COA High Availability & Fault Tolerance Flashcards
6 cards from real COA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 COA High Availability & Fault Tolerance flashcards as text
How many controller nodes are typically recommended as the minimum for quorum-based OpenStack HA?
Answer: 3
Three controller nodes are the minimum recommended for quorum, preventing split-brain scenarios in Galera and Pacemaker clusters.
What happens to a running instance during a successful OpenStack live migration?
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.
Which OpenStack alarming service evaluates metric thresholds and triggers actions for automated fault response?
Answer: Aodh
Aodh is OpenStack's alarming service that evaluates metric thresholds from Gnocchi and triggers notifications or Heat scaling actions.
What is the purpose of a floating IP in an OpenStack high availability architecture?
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.
Which HAProxy directive configures HTTP health checks against backend OpenStack API nodes?
Answer: option httpchk
The `option httpchk` directive tells HAProxy to send HTTP requests to backend OpenStack API nodes to detect unhealthy backends.
Which OpenStack project provides DNS as a service with support for highly available DNS backends?
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.