The answer is that the configuration register is set to 0x2142, which causes the router to ignore the startup configuration during boot. When a Cisco router boots with this register value, it loads only the default factory configuration, leaving all interfaces in an administratively down state because no 'no shutdown' commands from the startup-config are applied. On the CCNA 200-301 v2 exam, this scenario tests your understanding of the boot process and how the configuration register controls which configuration the router loads; a common trap is confusing 0x2142 with 0x2102, the default value that loads the startup configuration normally. The key memory tip is to think of the "42" in 0x2142 as "forget to" — as in, forget the startup config — leaving interfaces down until you manually copy the startup-config to the running-config and issue a 'no shutdown' on each interface.
CCNA Network Infrastructure and Connectivity Practice Question
This 200-301 practice question tests your understanding of network infrastructure and connectivity. 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.
Exhibit
R1# show version
Cisco IOS Software, 2800 Software (C2800NM-ADVIPSERVICESK9-M), Version 15.1(4)M10, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2016 by Cisco Systems, Inc.
Compiled Wed 30-Nov-16 14:46 by prod_rel_team
ROM: System Bootstrap, Version 12.4(13r)T11, RELEASE SOFTWARE (fc1)
R1 uptime is 2 minutes
System returned to ROM by power-on
System image file is "flash:c2800nm-advipservicesk9-mz.151-4.M10.bin"
Cisco 2811 (revision 53.51) with 253952K/8192K bytes of memory.
Processor board ID FCZ1511709Y
2 FastEthernet interfaces
2 Serial interfaces
1 Virtual Private Network (VPN) Module
125440K bytes of ATA CompactFlash (Read/Write)
Configuration register is 0x2142
Refer to the exhibit. An administrator notices that all interfaces on R1 are in an administratively down state. The administrator issues the show version command and sees the following output. What is the most likely cause of the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
R1# show version
Cisco IOS Software, 2800 Software (C2800NM-ADVIPSERVICESK9-M), Version 15.1(4)M10, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2016 by Cisco Systems, Inc.
Compiled Wed 30-Nov-16 14:46 by prod_rel_team
ROM: System Bootstrap, Version 12.4(13r)T11, RELEASE SOFTWARE (fc1)
R1 uptime is 2 minutes
System returned to ROM by power-on
System image file is "flash:c2800nm-advipservicesk9-mz.151-4.M10.bin"
Cisco 2811 (revision 53.51) with 253952K/8192K bytes of memory.
Processor board ID FCZ1511709Y
2 FastEthernet interfaces
2 Serial interfaces
1 Virtual Private Network (VPN) Module
125440K bytes of ATA CompactFlash (Read/Write)
Configuration register is 0x2142
A
The router IOS image is corrupted and needs to be reinstalled.
Why wrong: The exhibit shows a normal boot with a valid system image file and no errors. A corrupted image typically results in ROMmon mode or repeated reboots, not a successful boot with default interfaces.
B
The interfaces have been manually shut down in the running configuration, and the startup-config file is empty.
Why wrong: While interfaces could be shut down manually, the exhibit does not show a running configuration; it only shows the configuration register value. The 0x2142 setting provides a more direct and common cause for a default configuration with no startup-config loaded.
C
The router experienced a memory error during boot and failed to load the startup configuration.
Why wrong: The show version output does not indicate any memory error or CRC failure. If a memory error occurred, the router would typically display an error message or fail to boot entirely. The configuration register 0x2142 is a deliberate setting, not a sign of hardware failure.
D
The configuration register is set to 0x2142, causing the router to ignore the startup configuration.
This is directly confirmed by the last line of the exhibit: 'Configuration register is 0x2142'. This setting tells the router to bypass loading the startup-config from NVRAM, resulting in a clean slate where all interfaces are administratively down.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The configuration register is set to 0x2142, causing the router to ignore the startup configuration.
The configuration register value 0x2142 tells the router to ignore the startup configuration during boot, loading only the default factory configuration. This causes all interfaces to be in an administratively down state because no interface configurations from the startup-config are applied. The administrator sees the interfaces as administratively down because the default configuration does not include any 'no shutdown' commands.
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 router IOS image is corrupted and needs to be reinstalled.
Why it's wrong here
The exhibit shows a normal boot with a valid system image file and no errors. A corrupted image typically results in ROMmon mode or repeated reboots, not a successful boot with default interfaces.
✗
The interfaces have been manually shut down in the running configuration, and the startup-config file is empty.
Why it's wrong here
While interfaces could be shut down manually, the exhibit does not show a running configuration; it only shows the configuration register value. The 0x2142 setting provides a more direct and common cause for a default configuration with no startup-config loaded.
✗
The router experienced a memory error during boot and failed to load the startup configuration.
Why it's wrong here
The show version output does not indicate any memory error or CRC failure. If a memory error occurred, the router would typically display an error message or fail to boot entirely. The configuration register 0x2142 is a deliberate setting, not a sign of hardware failure.
✓
The configuration register is set to 0x2142, causing the router to ignore the startup configuration.
Why this is correct
This is directly confirmed by the last line of the exhibit: 'Configuration register is 0x2142'. This setting tells the router to bypass loading the startup-config from NVRAM, resulting in a clean slate where all interfaces are administratively down.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓The configuration register is set to 0x2142, causing the router to ignore the startup configuration.Correct answer▾
Why this is correct
This is directly confirmed by the last line of the exhibit: 'Configuration register is 0x2142'. This setting tells the router to bypass loading the startup-config from NVRAM, resulting in a clean slate where all interfaces are administratively down.
✗The router IOS image is corrupted and needs to be reinstalled.Wrong answer — click to see why▾
Why this is wrong here
Candidates may confuse a successful IOS boot with a corrupted image because both can lead to an unusable configuration, but the configuration register is the direct clue.
✗The interfaces have been manually shut down in the running configuration, and the startup-config file is empty.Wrong answer — click to see why▾
Why this is wrong here
Candidates may focus on the symptom (interfaces down) and hypothesize a manual configuration error, but they miss the clear hardware boot-parameter issue indicated by the config register.
✗The router experienced a memory error during boot and failed to load the startup configuration.Wrong answer — click to see why▾
Why this is wrong here
Candidates equate configuration loss with hardware faults, overlooking the intentional nature of the 0x2142 register value.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the specific effect of configuration register 0x2142 (ignoring startup-config) versus 0x2102 (normal boot), and the trap here is that candidates may confuse it with a corrupted IOS or manual shutdown, not realizing the register value directly causes the default interface state.
Trap categories for this question
Command / output trap
The exhibit shows a normal boot with a valid system image file and no errors. A corrupted image typically results in ROMmon mode or repeated reboots, not a successful boot with default interfaces.
Detailed technical explanation
How to think about this question
The configuration register is a 16-bit value stored in NVRAM that controls boot behavior; 0x2142 sets the boot field to ignore the startup configuration (bit 6 set to 1). When the router boots with this register, it loads the IOS from flash but skips the startup-config, resulting in a default configuration where all interfaces are administratively down. This is commonly used for password recovery, where the administrator must manually copy the startup-config to running-config and then change the register back to 0x2102.
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 200-301 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 200-301 question in full detail.
Network Infrastructure and Connectivity — This question tests Network Infrastructure and Connectivity — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The configuration register is set to 0x2142, causing the router to ignore the startup configuration. — The configuration register value 0x2142 tells the router to ignore the startup configuration during boot, loading only the default factory configuration. This causes all interfaces to be in an administratively down state because no interface configurations from the startup-config are applied. The administrator sees the interfaces as administratively down because the default configuration does not include any 'no shutdown' commands.
What should I do if I get this 200-301 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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