350-401 Security Practice Question
A network engineer is configuring MACsec on a point-to-point link between two Cisco Catalyst switches to provide Layer 2 encryption. The engineer wants to use a pre-shared key for authentication and ensure that the key is rotated periodically. Which MACsec component must be configured to specify the pre-shared key and the key rotation timer?
⚠ Common exam trap
Watch out — candidates often confuse MACsec key management with IPsec mechanisms like IKEv2 or crypto maps, when MACsec specifically uses MKA and a key chain for preshared keys and rotation.
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
✓
A MACsec key chain with a key string and a lifetime configured under the interface.
MACsec on Cisco switches uses a key chain to store the connectivity association key and its lifetime, which controls key rotation. The key chain is referenced under the interface with the mka key-chain command. This configuration provides the preshared key and periodic rotation required by the scenario, unlike IPsec mechanisms such as IKEv2 or crypto maps.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
An IKEv2 profile with a preshared key and a rekey timer applied to the interface.
Why it's wrong here
IKEv2 is used for IPsec VPNs, not MACsec. MACsec uses the MACsec Key Agreement (MKA) protocol with a key chain, not IKEv2. Applying an IKEv2 profile to a switch interface would not enable MACsec encryption or key rotation for Layer 2 traffic.
- ✗
A RADIUS server configuration with a shared secret and a session timeout applied to the interface.
Why it's wrong here
RADIUS is used for authentication, authorization, and accounting, not for MACsec key management. While MACsec can use 802.1X for key distribution, the scenario specifies a preshared key and key rotation, which are configured in a MACsec key chain, not a RADIUS shared secret.
- ✓
A MACsec key chain with a key string and a lifetime configured under the interface.
Why this is correct
MACsec on Cisco switches uses a key chain to store the connectivity association key (CAK) and its lifetime. The key chain is referenced under the interface with the mka key-chain command, and the lifetime controls key rotation. This satisfies the requirement for a preshared key and periodic rotation.
- ✗
A crypto map with a preshared key and a lifetime applied to the switch port.
Why it's wrong here
Crypto maps are used for IPsec VPNs on routers, not for MACsec on switches. MACsec configuration uses MKA and a key chain, not a crypto map. Applying a crypto map to a switch port would not provide Layer 2 encryption or the required key rotation.
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.
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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 Cisco exam blueprint
This 350-401 practice question is part of Courseiva's free Cisco 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 350-401 exam.