300-410 VPN Technologies Practice Question
A network engineer is configuring a site-to-site VPN between two Cisco IOS routers using IPsec. The engineer wants to ensure that only traffic from the 10.1.1.0/24 network to the 10.2.2.0/24 network is encrypted. Which type of ACL must be used in the crypto map to define the interesting traffic?
⚠ Common exam trap
The trap here is using a standard ACL or a deny statement, misunderstanding that the crypto ACL must be an extended ACL that permits the specific traffic.
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
✓
An extended ACL that permits IP traffic from 10.1.1.0/24 to 10.2.2.0/24.
In Cisco IPsec configuration, the crypto map references an extended ACL to identify interesting traffic. The ACL must permit IP traffic from the local subnet to the remote subnet. This ensures that only packets matching those criteria are encrypted and sent through the VPN tunnel. Standard ACLs or overly broad ACLs are incorrect.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
A standard ACL that permits the 10.1.1.0/24 network.
Why it's wrong here
Standard ACLs can only match source addresses and cannot specify destination addresses or protocols. For IPsec, the ACL must define both source and destination, and typically the protocol (IP). Therefore, a standard ACL is not suitable for defining interesting traffic in a crypto map.
- ✗
An extended ACL that denies IP traffic from 10.1.1.0/24 to 10.2.2.0/24.
Why it's wrong here
A deny statement in the crypto ACL would exclude that traffic from encryption. The ACL in a crypto map is used to match traffic that should be encrypted; it should permit the desired traffic. Denying it would prevent the VPN from encrypting the specified subnets.
- ✓
An extended ACL that permits IP traffic from 10.1.1.0/24 to 10.2.2.0/24.
Why this is correct
For IPsec site-to-site VPNs, the crypto map ACL must be an extended ACL that defines the interesting traffic. It should permit IP traffic from the local subnet to the remote subnet. This ACL is used to match packets that need encryption. A standard ACL cannot specify destination addresses or protocols, so it is insufficient.
- ✗
A named ACL that permits all IP traffic.
Why it's wrong here
Permitting all IP traffic would cause all traffic to be encrypted, not just the specified subnets. This could lead to unnecessary encryption and potential routing issues. The requirement is to encrypt only traffic between the two specific subnets, so a more specific ACL is needed.
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.
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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 300-410 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 300-410 exam.