350-501 Architecture Practice Question
An SP network uses NTP for synchronization. To secure NTP, which authentication mode should be used?
⚠ Common exam trap
Cisco often tests the distinction between NTPv3 symmetric key (manual) and NTPv4 autokey (automated), leading candidates to incorrectly choose symmetric key because they overlook the 'secure' requirement in the question.
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
✓
NTPv4 autokey
NTPv4 autokey (Option A) is the correct answer because it provides a secure, automated key distribution mechanism using public-key cryptography (RFC 5906). This eliminates the need for manual key exchange, making it the recommended authentication mode for securing NTP in service provider networks.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
NTPv4 autokey
Why this is correct
NTPv4 autokey provides strong cryptographic authentication.
- ✗
NTPv3 symmetric key
Why it's wrong here
NTPv3 symmetric key is less secure and not recommended.
- ✗
NTPv4 with SHA-1
Why it's wrong here
SHA-1 is not standard for NTP authentication.
- ✗
NTPv4 with MD5
Why it's wrong here
MD5 is not recommended due to vulnerabilities.
Quick reference
Asymmetric Encryption Algorithm Comparison
| Algorithm | Key Exchange | Signatures | Equivalent Security Key | Notes |
|---|---|---|---|---|
| RSA-3072 | Yes | Yes | 128-bit | Widely deployed; slow for bulk data |
| ECDSA P-256 | No | Yes | 128-bit | Fast signatures; standard TLS certs |
| ECDH / ECDHE | Yes | No | 128-bit | Perfect forward secrecy in TLS 1.3 |
| DH / DHE | Yes | No | 128-bit (3072-bit key) | Replaced by ECDHE in modern TLS |
| Ed25519 | No | Yes | ~128-bit | SSH keys, modern PKI |
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-501 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 350-501 exam.