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Difficulty: MediumRemote Access and Out-of-Band Management

Following a major power interruption at an off-site facility, a core router fails to initialize its IP protocol stack, rendering all in-band network interfaces completely unreachable. Which of the following access methods allows a network administrator to establish direct command-line interface (CLI) access to diagnose the device's boot process?

  1. Connecting via an out-of-band serial console server linked to an external cellular modem connectionAnswer
  2. B
    Initiating an SSH session over TCP port 22 targeting the router's loopback interface IP address
  3. C
    Establishing a Telnet session over TCP port 23 using the default gateway address of the primary LAN segment
  4. D
    Accessing the device web portal using an HTTPS session over TCP port 443 across the primary WAN link

Answer

Connecting via an out-of-band serial console server linked to an external cellular modem connection provides independent access to the device when all network interfaces and IP stacks are down.
Out-of-band (OOB) management utilizes a dedicated access channel separate from the primary data network. Connecting through an RS-232 serial console port via a console server and cellular modem provides direct access to the device's serial bus and command-line interface, allowing administrators to monitor low-level boot messages and reconfigure settings even when the primary IP stack is inactive.

Step-by-Step Solution

1
Analyze the operational constraint described in the scenario.
The core router's IP stack has failed to initialize, making all in-band management methods (SSH, Telnet, HTTPS) inaccessible due to lack of network layer connectivity.
In-band management requires functional Layer 3 IP routing and transport layer service operation on the target device.
2
Identify the required access method designed to bypass the primary network path.
Out-of-Band (OOB) management provides direct physical or secondary channel connectivity to device hardware.
OOB access operates independently of the primary LAN/WAN infrastructure and does not depend on the router's operating network interfaces.
3
Select the option that implements a true out-of-band management pathway.
Using a console server connected to the router's RS-232 serial console port paired with a cellular modem allows administrators to connect directly to the CLI hardware bus.
The serial console interface exposes low-level boot diagnostic logs (such as ROMMON or BIOS messages) without requiring an IP stack.

Key Concept

Out-of-Band (OOB) Management
Estimated Time:1m 15s
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Topics

Remote Access and Out-of-Band Management

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