ACA High Availability & Redundancy 2 — Questions and Answers
Question 1: What does 'Hitless Switchover' mean in the context of AudioCodes HA?
- The switchover occurs so quickly that SIP registration timers do not expire
- Active calls are preserved and continue without interruption after failover to the standby unit (Correct answer)
- The standby unit takes over without requiring a physical network cable change
- Configuration is applied to the standby unit without interrupting the active unit's traffic
Correct answer: Active calls are preserved and continue without interruption after failover to the standby unit
Hitless switchover means that in-progress calls are maintained through the failover event, with media streams continuing on the standby unit.
Question 2: What mechanism does the AudioCodes standby unit use to detect that the active unit has failed?
- Periodic ICMP ping to the active unit's management IP
- Keep-alive messages exchanged over the dedicated HA link (Correct answer)
- SIP OPTIONS polling sent every 30 seconds
- SNMP heartbeat traps sent to a centralized NMS
Correct answer: Keep-alive messages exchanged over the dedicated HA link
Keep-alive messages over the dedicated HA synchronization link allow the standby unit to detect active unit failure and initiate switchover.
Question 3: In AudioCodes HA, what is a 'Manual Switchover' used for?
- Forcing a failover during planned maintenance without waiting for a failure event (Correct answer)
- Resetting the standby unit to factory defaults before re-pairing
- Migrating the HA pair to a new subnet without service interruption
- Upgrading firmware on the active unit while keeping the standby on the old version
Correct answer: Forcing a failover during planned maintenance without waiting for a failure event
Manual switchover allows administrators to gracefully transfer the active role to the standby unit for maintenance, upgrades, or testing without an actual failure.
Question 4: What is the recommended approach for upgrading firmware on an AudioCodes HA pair to minimize downtime?
- Upgrade both units simultaneously to avoid version mismatches
- Upgrade the standby unit first, perform a manual switchover, then upgrade the originally-active unit (Correct answer)
- Disable HA, upgrade both units independently, then re-enable HA
- Upload new firmware to the EMS and let it push to both units automatically at 2 AM
Correct answer: Upgrade the standby unit first, perform a manual switchover, then upgrade the originally-active unit
Upgrading the standby first, then switching over, then upgrading the other unit allows rolling upgrades with minimal (or zero) service disruption.
Question 5: Which AudioCodes HA state indicates the unit is fully synchronized and prepared to assume the active role?
- Initializing
- Hot Standby (Correct answer)
- Warm Standby
- Passive Monitor
Correct answer: Hot Standby
A unit in 'Hot Standby' state is fully synchronized with the active unit and can assume the active role immediately without any delay or data loss.
Question 6: What happens to SIP registrations on endpoints when an AudioCodes HA failover occurs with hitless switchover enabled?
- All SIP endpoints must re-register because the standby unit uses a different IP address
- Registrations are preserved because the standby takes the virtual IP and retains the registration database (Correct answer)
- Endpoints receive a SIP 503 Service Unavailable and automatically retry after 30 seconds
- Only endpoints registered within the last 60 seconds are preserved; older registrations expire
Correct answer: Registrations are preserved because the standby takes the virtual IP and retains the registration database
Because the standby assumes the virtual IP and has a synchronized registration database, existing SIP registrations are maintained without requiring re-registration.
Question 7: In an AudioCodes HA pair, which unit is responsible for sending SNMP traps and syslog messages to the NMS during normal operation?
- Both units send identical traps and logs simultaneously for redundancy
- Only the active unit sends traps and logs; the standby suppresses these events (Correct answer)
- The standby unit handles all management plane traffic while the active handles media
- The EMS server polls both units and aggregates the results into a single stream
Correct answer: Only the active unit sends traps and logs; the standby suppresses these events
During normal operation, only the active unit generates SNMP traps and syslog messages; after failover, the newly active unit takes over this responsibility.
ACA High Availability & Redundancy 2
What does 'Hitless Switchover' mean in the context of AudioCodes HA?