Quick Answer
The answer is AES and 3DES, as both are symmetric encryption algorithms that use the same key for encryption and decryption. AES, or Advanced Encryption Standard, is the modern industry standard offering strong security with key sizes of 128, 192, or 256 bits, while 3DES, or Triple Data Encryption Standard, applies the DES cipher three times per block to increase effective key length. On the Cisco CyberOps Associate 200-201 exam, this concept tests your ability to distinguish symmetric from asymmetric algorithms, often appearing in questions about encryption protocols used in network security. A common trap is confusing 3DES with DES or assuming AES is asymmetric because of its widespread use in public-key contexts. Remember the memory tip: “Same key for both sides” is the hallmark of symmetric encryption, and both AES and 3DES fit that rule—think of them as the “twin locks” of the symmetric world.
This 200-201 practice question tests your understanding of security concepts. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which TWO of the following are symmetric encryption algorithms? (Choose two.)
AES
AES is a symmetric block cipher.
RSA
Why wrong: RSA is an asymmetric algorithm.
Diffie-Hellman
Why wrong: Diffie-Hellman is a key exchange protocol, not symmetric encryption.
ECC
Why wrong: ECC (Elliptic Curve Cryptography) is asymmetric.
3DES
3DES is a symmetric encryption algorithm.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
AES
AES (Advanced Encryption Standard) is a symmetric encryption algorithm, meaning it uses the same key for both encryption and decryption. It is widely adopted due to its strong security and efficiency, with key sizes of 128, 192, or 256 bits. 3DES (Triple Data Encryption Standard) is also symmetric, applying the DES cipher three times to each data block, effectively increasing key length and security over single DES.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
AES
Why this is correct
AES is a symmetric block cipher.
Related concept
Read the scenario before looking for a memorised answer.
RSA
Why it's wrong here
RSA is an asymmetric algorithm.
Diffie-Hellman
Why it's wrong here
Diffie-Hellman is a key exchange protocol, not symmetric encryption.
ECC
Why it's wrong here
ECC (Elliptic Curve Cryptography) is asymmetric.
3DES
Why this is correct
3DES is a symmetric encryption algorithm.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Cisco often tests the distinction between symmetric encryption, asymmetric encryption, and key exchange protocols, so candidates mistakenly select Diffie-Hellman or ECC as encryption algorithms when they are actually used for key agreement or asymmetric operations.
Detailed technical explanation
Symmetric encryption algorithms like AES operate on fixed-size blocks (e.g., 128 bits for AES) using modes such as CBC, GCM, or CTR to handle data larger than a single block. 3DES uses a key length of 168 bits (three 56-bit DES keys) but is now considered deprecated due to its slower performance and vulnerability to meet-in-the-middle attacks, with NIST officially disallowing it after 2023. In contrast, asymmetric algorithms like RSA rely on the mathematical difficulty of factoring large prime numbers, making them computationally expensive for bulk data encryption, which is why symmetric ciphers are preferred for encrypting large volumes of data in protocols like TLS.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the 200-201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Security Concepts — This question tests Security Concepts — Read the scenario before looking for a memorised answer..
The correct answer is: AES — AES (Advanced Encryption Standard) is a symmetric encryption algorithm, meaning it uses the same key for both encryption and decryption. It is widely adopted due to its strong security and efficiency, with key sizes of 128, 192, or 256 bits. 3DES (Triple Data Encryption Standard) is also symmetric, applying the DES cipher three times to each data block, effectively increasing key length and security over single DES.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This 200-201 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 200-201 exam.
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