350-701 Security Concepts Practice Question
A security administrator is evaluating symmetric encryption algorithms for a new VPN deployment. Which algorithm uses a 128-bit block size and supports key sizes of 128, 192, and 256 bits?
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
✓
AES
AES is a symmetric block cipher with a fixed block size of 128 bits and key sizes of 128, 192, or 256 bits.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
3DES
Why it's wrong here
3DES has a block size of 64 bits and uses 56-bit keys (168 bits effective with three keys).
- ✓
AES
Why this is correct
Correct answer. AES meets the described parameters.
- ✗
RSA
Why it's wrong here
RSA is an asymmetric algorithm, not symmetric.
- ✗
MD5
Why it's wrong here
MD5 is a hash function, not encryption.
Quick reference
Symmetric Encryption Algorithm Comparison
| Algorithm | Key Size | Block Size | Status | Notes |
|---|---|---|---|---|
| AES-128 | 128-bit | 128-bit | Current standard | NIST approved; WPA3, TLS |
| AES-256 | 256-bit | 128-bit | Current standard | Preferred for sensitive / govt data |
| 3DES | 112-bit effective | 64-bit | Deprecated (2023) | Replaced by AES |
| DES | 56-bit | 64-bit | Broken | Cracked in < 24 h; never deploy |
| ChaCha20 | 256-bit | Stream cipher | Current | TLS 1.3, WireGuard |
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-701 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 350-701 exam.