- A
The ifIndex for Loopback0 is 3.
The output clearly shows Loopback0 with ifIndex 3.
- B
The ifIndex values are assigned sequentially starting from 0.
Why wrong: The ifIndex values start from 1 and are not necessarily sequential (note the jump to 10).
- C
GigabitEthernet0/0 has ifIndex 2.
Why wrong: GigabitEthernet0/0 has ifIndex 1.
- D
Tunnel0 has ifIndex 3.
Why wrong: Tunnel0 has ifIndex 10.
Question 643 of 2,152
How to Map ifIndex to Interfaces with show snmp mib ifmib ifindex
This 300-410 practice question tests your understanding of snmp troubleshooting. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
A network engineer runs the following command on Router R1:
R1# show snmp mib ifmib ifindex
ifIndex: 1
Interface: GigabitEthernet0/0
Description: GigabitEthernet0/0
ifIndex: 2
Interface: GigabitEthernet0/1
Description: GigabitEthernet0/1
ifIndex: 3
Interface: Loopback0
Description: Loopback0
ifIndex: 10
Interface: Tunnel0
Description: Tunnel0
Based on this output, which statement is correct?
Quick Answer
The answer is that the ifIndex for Loopback0 is 3. This is correct because the output of the show snmp mib ifmib ifindex command directly displays the SNMP ifIndex-to-interface mapping, where each interface is assigned a unique numeric identifier used by SNMP managers for monitoring and polling. In the provided output, Loopback0 is explicitly listed with ifIndex 3, confirming the mapping. On the Cisco CCNP ENARSI 300-410 exam, this command tests your understanding of SNMP interface indexing and how it differs from interface numbering—a common trap is assuming ifIndex values are sequential or match the interface number, but as shown, Tunnel0 jumps to ifIndex 10. Remember that ifIndex values are assigned dynamically and can be non-contiguous, so always read the output carefully rather than guessing. A helpful memory tip: ifIndex is like a social security number for each interface—unique, but not in order.
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 ifIndex for Loopback0 is 3.
The output of 'show snmp mib ifmib ifindex' displays the ifIndex values assigned to each interface by the SNMP agent. The table clearly shows Loopback0 with ifIndex 3, making option A correct. ifIndex values are not guaranteed to be sequential or start from 0; they are assigned dynamically and can have gaps, as seen with Tunnel0 having ifIndex 10.
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.
- ✓
The ifIndex for Loopback0 is 3.
Why this is correct
The output clearly shows Loopback0 with ifIndex 3.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The ifIndex values are assigned sequentially starting from 0.
Why it's wrong here
The ifIndex values start from 1 and are not necessarily sequential (note the jump to 10).
- ✗
GigabitEthernet0/0 has ifIndex 2.
Why it's wrong here
GigabitEthernet0/0 has ifIndex 1.
- ✗
Tunnel0 has ifIndex 3.
Why it's wrong here
Tunnel0 has ifIndex 10.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that ifIndex values are assigned sequentially starting from 0 or 1 without gaps, but the output shows non-sequential values (e.g., Tunnel0 with ifIndex 10) to trap candidates who assume a simple 1-to-1 order.
Detailed technical explanation
How to think about this question
The ifIndex is defined in RFC 2863 (IF-MIB) as a unique integer identifier for each interface, assigned by the SNMP agent at boot time or upon interface creation. It is not required to be contiguous; gaps can occur due to interface removal or dynamic creation (e.g., tunnels). In real-world scenarios, monitoring tools rely on ifIndex to correlate SNMP traps and performance data, so understanding that ifIndex values are persistent but not sequential is critical for accurate network management.
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.
TExam Day Tips
- 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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
SNMP Troubleshooting — study guide chapter
Learn the concepts, then practise the questions
- →
SNMP Troubleshooting practice questions
Targeted practice on this topic area only
- →
All 300-410 questions
2,152 questions across all exam domains
- →
Cisco CCNP ENARSI 300-410 study guide
Full concept coverage aligned to exam objectives
- →
300-410 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related 300-410 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Layer 3 Technologies practice questions
Practise 300-410 questions linked to Layer 3 Technologies.
EIGRP Troubleshooting practice questions
Practise 300-410 questions linked to EIGRP Troubleshooting.
OSPF Troubleshooting (v2/v3) practice questions
Practise 300-410 questions linked to OSPF Troubleshooting (v2/v3).
BGP Troubleshooting practice questions
Practise 300-410 questions linked to BGP Troubleshooting.
Route Redistribution practice questions
Practise 300-410 questions linked to Route Redistribution.
Policy-Based Routing (PBR) practice questions
Practise 300-410 questions linked to Policy-Based Routing (PBR).
VRF-Lite practice questions
Practise 300-410 questions linked to VRF-Lite.
Route Maps and Route Filtering practice questions
Practise 300-410 questions linked to Route Maps and Route Filtering.
Administrative Distance practice questions
Practise 300-410 questions linked to Administrative Distance.
Route Summarization practice questions
Practise 300-410 questions linked to Route Summarization.
Bidirectional Forwarding Detection (BFD) practice questions
Practise 300-410 questions linked to Bidirectional Forwarding Detection (BFD).
VPN Technologies practice questions
Practise 300-410 questions linked to VPN Technologies.
Practice this exam
Start a free 300-410 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this 300-410 question test?
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: The ifIndex for Loopback0 is 3. — The output of 'show snmp mib ifmib ifindex' displays the ifIndex values assigned to each interface by the SNMP agent. The table clearly shows Loopback0 with ifIndex 3, making option A correct. ifIndex values are not guaranteed to be sequential or start from 0; they are assigned dynamically and can have gaps, as seen with Tunnel0 having ifIndex 10.
What should I do if I get this 300-410 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Keep practising
More 300-410 practice questions
- Drag and drop the steps to negotiate an IKEv2 IPsec site-to-site tunnel into the correct order, from first to last.
- Drag and drop the steps to troubleshoot an IPsec site-to-site VPN adjacency failure into the correct order, from first t…
- Drag and drop the steps to verify and validate the operational state of an IPsec site-to-site VPN into the correct order…
- Consider the following configuration snippet: ip cef ! interface GigabitEthernet0/0 ip address 10.0.0.1 255.255.255.25…
- A router is configured with 'logging host 10.1.1.100' and 'logging trap informational'. The engineer notices that syslog…
- Drag and drop the steps to configure a GRE tunnel for IPv6 over IPv4 into the correct order, from first to last.
Last reviewed: Jul 4, 2026
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.