CCNA Network Infrastructure and Connectivity Practice Question
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?
⚠ Common exam trap
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.
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 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.
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
A corrupted IOS image would prevent the router from completing a normal boot sequence. The exhibit shows a successful boot message, a valid IOS filename (e.g., c2900-universalk9-mz.SPA.152-4.M5), and the router reaching user EXEC mode, which is impossible if the image were corrupt. Corruption typically forces the router into ROMmon (ROM Monitor mode) or causes a boot loop, not a clean start 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.
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?”
Go deeper
Related to this question
Learn chapter
VTP Versions and Configuration
Key term
Interface
An interface is a point of connection or interaction between two systems, devices, or software components that allows them to exchange information or signals.
Key term
Router
A router is a networking device that connects different networks together and directs data traffic between them by choosing the best path for data to travel.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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