156-315.81.20 ClusterXL and VRRP High Availability Practice Question
An administrator is configuring a ClusterXL High Availability (HA) solution. Which mechanism does the cluster use to ensure that the standby member can take over traffic seamlessly if the active member fails?
⚠ Common exam trap
Candidates frequently confuse general network routing with State Synchronization, incorrectly believing that standard routing tables alone are enough to maintain active TCP sessions during a failover.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The State Synchronization (Sync) network replicates kernel tables, ensuring the standby unit possesses an identical connection table.
ClusterXL High Availability maintains state synchronization via the State Synchronization network (Sync). By replicating connection tables, sequence numbers, and NAT translations, the standby member can assume the active role without dropping existing TCP connections. This ensures high availability and minimal downtime during failover events. Understanding this synchronization process is critical for troubleshooting traffic drops that occur specifically during transition states between cluster members.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The cluster uses Gratuitous ARP to update the upstream switch MAC address tables with the virtual IP address.
Why it's wrong here
Gratuitous ARP is used to update switches regarding MAC address ownership during a failover, but it is not the mechanism for state synchronization itself. While essential for directing traffic, it does not provide the connection state data required for seamless session preservation between the primary and secondary security gateways.
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The cluster utilizes the Security Gateway Control Protocol (SGCP) to synchronize session states and kernel tables between all active cluster members.
Why it's wrong here
While SGCP is the underlying protocol for cluster communication, the specific mechanism for maintaining seamless session continuity is the State Synchronization (Sync) network. SGCP facilitates health monitoring and configuration management, but it is the actual synchronization of state tables that allows for transparent failover of active connections.
- ✓
The State Synchronization (Sync) network replicates kernel tables, ensuring the standby unit possesses an identical connection table.
Why this is correct
The Sync network is the dedicated path for copying critical connection state information from the active to the standby member. By keeping the standby's connection table updated with the active unit's state, the firewall ensures that traffic flow continues uninterrupted post-failover, which is the primary objective of HA configuration.
- ✗
The cluster uses VRRP priority increments to negotiate which member maintains the connection state in the kernel.
Why it's wrong here
VRRP priority is used for virtual router election and master/backup determination in Layer 3 environments. It does not handle the synchronization of state tables or the preservation of TCP/UDP connections. Relying on VRRP for state management would fail to preserve existing sessions during a transition between members.
Visual reference
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Check Point exam blueprint
This 156-315.81.20 practice question is part of Courseiva's free Check Point certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 156-315.81.20 exam.