easyMultiple Choice
300-410 Practice Question: Runs the following command to troubleshoot an…
A network engineer runs the following command to troubleshoot an IPsec Site-to-Site VPN issue:
R1# show crypto ipsec transform-set
Transform set combined-des-sha: { esp-des esp-sha-hmac } will negotiate = { Tunnel, }, Transform set myset: { esp-3des esp-sha-hmac } will negotiate = { Tunnel, }, Transform set strong: { esp-aes 256 esp-sha-hmac } will negotiate = { Tunnel, },
What does this output indicate?
⚠ Common exam trap
Cisco often tests the candidate's awareness of deprecated or weak cryptographic algorithms (like DES) versus strong ones (like AES), and the trap here is assuming that all listed transform sets are equally valid or that the missing mode keyword indicates a misconfiguration.
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 transform set 'combined-des-sha' uses DES, which is not recommended due to security vulnerabilities.
The output shows three transform sets, including 'combined-des-sha', which uses DES (Data Encryption Standard) with a 56-bit key. DES is considered cryptographically weak and has been deprecated due to known vulnerabilities, such as susceptibility to brute-force attacks. Cisco recommends using AES or 3DES as a minimum for production IPsec VPNs, making option B correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
All transform sets are using strong encryption and are acceptable for production.
Why it's wrong here
The output lists three transform sets including esp-des, which is weak and unsuitable for production; the command merely displays configured sets and their negotiation modes, not a security assessment. Claiming all are strong ignores the DES entry, which would only be acceptable in legacy interoperability scenarios.
- ✓
The transform set 'combined-des-sha' uses DES, which is not recommended due to security vulnerabilities.
Why this is correct
The output lists transform sets and their proposals; combined-des-sha negotiates ESP with DES encryption and SHA-HMAC. DES uses a 56-bit key, which is cryptographically weak, so its presence is flagged as a security concern rather than a functional fault.
- ✗
The transform sets are not configured correctly because they do not specify the mode.
Why it's wrong here
Each transform set shows 'will negotiate = { Tunnel, }', confirming tunnel mode is specified, so the sets are not missing mode configuration. Mode is set separately from the transform set itself, and this output already reflects tunnel mode being selected.
- ✗
The transform set 'strong' is not supported because it uses AES 256.
Why it's wrong here
AES 256 is fully supported by the platform; the output simply lists esp-aes 256 as a configured proposal. Unsupported algorithms would not appear in the transform-set listing at all, so this statement misreads the display.
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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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.