The answer is HMAC-MD5-96. When a user is configured with "auth md5" in SNMPv3, the protocol defaults to the HMAC-MD5-96 algorithm for authentication, which produces a 96-bit message digest to verify message integrity and origin. This is defined in RFC 3414 and is the standard behavior because MD5 was the original hash specified for SNMPv3's User-based Security Model (USM). On the Cisco CCNP ENARSI 300-410 exam, this often appears in troubleshooting scenarios where authentication failures occur due to mismatched algorithms—a common trap is assuming "auth md5" uses full MD5 rather than the truncated HMAC variant. Remember that SNMPv3 always truncates the hash to 96 bits for both MD5 and SHA, so the "96" in the algorithm name is the key detail. A useful memory tip: think of "MD5-96" as "MD5 minus 32 bits," since MD5 normally produces 128 bits, but SNMPv3 clips it down to 96 for efficiency.
300-410 SNMP Troubleshooting Practice Question
This 300-410 practice question tests your understanding of snmp troubleshooting. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
When troubleshooting SNMPv3 authentication failures, which default HMAC algorithm is used if the user is configured with "auth md5"?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
HMAC-MD5-96
SNMPv3 uses HMAC-MD5-96 for authentication when MD5 is specified.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
HMAC-SHA-96
Why it's wrong here
HMAC-SHA-96 is used when SHA is configured, not MD5.
✓
HMAC-MD5-96
Why this is correct
RFC 3414 defines HMAC-MD5-96 as the authentication protocol for usmHMACMD5AuthProtocol.
Related concept
Read the scenario before looking for a memorised answer.
✗
HMAC-SHA-256
Why it's wrong here
HMAC-SHA-256 is not a standard SNMPv3 authentication protocol; only MD5 and SHA (96-bit) are defined in the base RFC.
✗
No HMAC is used; MD5 is used directly.
Why it's wrong here
SNMPv3 always uses HMAC for authentication, not raw MD5.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 300-410 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
Identify which 300-410 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
SNMP Troubleshooting — This question tests SNMP Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: HMAC-MD5-96 — SNMPv3 uses HMAC-MD5-96 for authentication when MD5 is specified.
What should I do if I get this 300-410 question wrong?
Identify which 300-410 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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