CND Practice Question: Network Security Controls Protocols And Devices
A network administrator is configuring a high-availability pair of firewalls in active/passive mode using virtual router redundancy protocol (VRRP). During a failover event, active TCP sessions drop, forcing users to re-authenticate to internal applications. Which firewall feature must be enabled to maintain stateful session continuity across the 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
✓
Stateful session synchronization (State Sync / HA heartbeat link)
Stateful failover (or session synchronization/state sync) synchronizes connection tables, NAT mappings, and IPsec security associations from the active firewall to the standby firewall in real-time, preventing dropped sessions during a failover.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Network Address Translation (NAT) pool overloading
Why it's wrong here
NAT overload (PAT) allows multiple internal IPs to share a public IP, but it does not maintain active connection tables across a firewall cluster failover.
- ✗
Asymmetric routing bypass mode
Why it's wrong here
Asymmetric routing bypass allows a firewall to accept traffic where the return path is different, but it does not synchronize state tables between two clustered firewalls.
- ✓
Stateful session synchronization (State Sync / HA heartbeat link)
Why this is correct
Session synchronization replicates active connection states to the standby unit so it can seamlessly take over existing TCP flows without interruption.
- ✗
Dynamic DNS update propagation
Why it's wrong here
Dynamic DNS updates map hostnames to IP addresses; they do not synchronize active Layer 4 firewall connection states.
Visual reference
Quick reference
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
About these practice questions
This CND question is part of Courseiva's 323-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official EC-Council exam blueprint
This CND practice question is part of Courseiva's free EC-Council 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 CND exam.