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Difficulty: MediumRemote Access and Out-of-Band Management

A network administrator loses all network access to a remote branch router following a fiber cut on the primary WAN circuit. The administrator needs to establish a command-line interface (CLI) session to inspect the router's boot process and interface status without relying on the down IP network link. Which mechanism provides remote management capabilities in this out-of-band scenario?

  1. A terminal server attached to the router's serial console port and connected to an external cellular modemAnswer
  2. B
    An SSH session initiated over TCP port 23 directed to the router's primary Ethernet interface IP address
  3. C
    An unencrypted UDP stream directed to port 22 across the active local area switch interface
  4. D
    An SNMPv1 GET request transmitted over UDP port 161 across the standard default gateway path

Answer

Connecting a terminal server to the router's serial console port backed by a cellular modem provides true out-of-band management isolated from primary network outages.
Out-of-band (OOB) management provides a dedicated, alternative access path to network hardware that functions independently of the primary data network. A cellular modem connected to a terminal server allows direct serial console connection to the router's CLI, enabling administrators to troubleshoot even when the main WAN fiber link is completely cut.

Step-by-Step Solution

1
Analyze the operational failure constraint.
The primary WAN link is down due to a fiber cut, rendering all in-band IP communication mechanisms inaccessible.
In-band management relies on the operational state of the primary network interfaces and routing infrastructure.
2
Identify the required management architecture.
An out-of-band (OOB) solution is required to bypass the main network path entirely.
Out-of-band management utilizes an independent physical or wireless communication channel (e.g., cellular network or POTS dial-up) to access device console/serial ports.
3
Evaluate the valid technical deployment.
A cellular modem paired with a terminal server connected directly to the device's RS-232/RJ-45 console port provides direct CLI access regardless of primary WAN state.
This setup allows system administrators to troubleshoot hardware, view system boot logs, and reconfigure settings remotely during total network outages.

Key Concept

Out-of-Band (OOB) Management
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Topics

Remote Access and Out-of-Band Management

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