4A0-265 Nokia Optical Diagnostics and Troubleshooting Exam Free Practice Exam Questions (2025 Updated)

On a bidirectional optical amplifier configuration, the Wavelength Tracker detection points are the LINE and SIG interfaces. The Wavelength Tracker is a feature that monitors the wavelength of each channel on the optical amplifier and provides feedback to the control system. The Wavelength Tracker can detect wavelength drifts, channel failures, or channel additions or removals on both directions of the optical amplifier. The LINE interface is the input/output port for the optical line signal, while the SIG interface is the input/output port for the optical signal from/to the transponder. The other options are incorrect because the LINEOUT and SIGOUT interfaces are not Wavelength Tracker detection points, and an optical amplifier has Wavelength Tracker detection points. References: Nokia Optical Diagnostics and Troubleshooting Course, OAM and Diagnostics Guide

The statement that is false is that no OSC-related alarms will raise on the local node. OSC stands for Optical Supervisory Channel, which is a dedicated wavelength used for out-of-band signaling and management of optical network elements. If a node is experiencing a little unexpected attenuation over the OSC transmit direction, it means that the OSC signal is weaker than expected when it reaches the adjacent node. This can cause a “Data Link Down” alarm to raise on the adjacent node, indicating that the OSC communication link is broken or degraded. However, this can also cause an “OSC Power Low” alarm to raise on the local node, indicating that the OSC transmit power is below the threshold. Therefore, there will be OSC-related alarms on both nodes. The other statements are true because a power adjustment action will fail on the local node due to insufficient OSC power, and traffic will pass between the nodes as long as there is no other issue affecting the data channels. References: Nokia Optical Diagnostics and Troubleshooting Course, Optical Supervisory Channel Module product data sheet

The Customer Release Notes (CRNs) document collects documented solved known issues, new issues discovered after the product software has been released, as well as software upgrade procedures and firmware details. This document is useful for troubleshooting because it can help identify if a problem is related to a known issue or a software bug, and if there is a workaround or a solution available. The CRNs also provide information about the software compatibility and interoperability of different Nokia products and platforms. The other options are incorrect because the EPTUG and the UPG do not contain information about known issues, and the CRNs do not provide instructions for automated provisioning, commissioning, and power balancing functions. References: Nokia Optical Diagnostics and Troubleshooting Course, Nokia Optical Diagnostics and Troubleshooting Exam

The statement that best describes the Forward Error Correction (FEC) technique is C. FEC is a technique used in digital communication to improve the accuracy and reliability of data transmission. By adding redundant information to the transmitted data, FEC enables the receiver to detect and correct errors without retransmission or other error correction techniques11. FEC is effective only above a specified OSNR threshold, which is the minimum optical signal-to-noise ratio required for error-free transmission with FEC enabled. If the OSNR falls below this threshold, FEC cannot correct all errors and data quality degrades significantly. References : Nokia Optical Diagnostics and Troubleshooting Course | Nokia, Optical User Guide - Nokia, Forward Error Correction (FEC) - Online Tutorials Library

The command show xc 1 displays a list of cross-connections, including A-end, Z-end, frequency, ID number, OCH trail name, and administrative/operational states. A cross-connection is a logical connection between two ports on an optical network element that allows the transmission of an optical signal from one port to another. The command can be used to view the configuration and status of the cross-connections on a node or a network. The other options are incorrect because they either describe a different command or provide incorrect information. References: Nokia Optical Diagnostics and Troubleshooting Course, OAM and Diagnostics Guide

The command show interface am2125a 1/6/lineout detail is used to retrieve the total output power level of the AM2125A amplifier module. This command displays detailed information about the lineout interface, including the current optical power, wavelength, and status. The total output power level is shown as Output Power (dBm) in the output of this command1. References : Nokia Optical Diagnostics and Troubleshooting Course | Nokia

 The available output optical power range is the same as in question 5, since the EPT Power Management Report refers to the same ingress amplifier with the same settings and parameters. Therefore, the answer is also A, -0.6 to 1.72 dB. References : Nokia Optical Diagnostics and Troubleshooting Course | Nokia, EPT Power Management Report | Nokia

1-Day PMs are one of the types of PM data that can be retrieved from an optical network element. 1-Day PMs show measurements collected over the preceding 24 hours, with each hour being a bin. Up to 8 bins are available for data storing, which means that only the most recent 8 hours of data can be accessed. The other types of PM data are 15-Minute PMs, which show measurements collected over the preceding 15 minutes, with each minute being a bin, and Total PMs, which show measurements collected since the last reset of the PM counters. References: Nokia Optical Diagnostics and Troubleshooting Course, Nokia 1830 PSS-32 and PSS-16 Photonic Service Switch Release 8.0 Performance Monitoring Reference Guide

The exhibit shows a diagram of a network with two nodes, Node A and Node B, connected by a fiber span. The diagram also shows the power readings at different points of the span. The calculated span loss from Node A to Node B is the difference between the output power at Node A and the input power at Node B. According to the diagram, the output power at Node A is +3.5 dBm and the input power at Node B is -4.5 dBm. Therefore, the span loss from Node A to Node B is 3.5 - (-4.5) = 8.0 dB.

 The statement that an “Incoming SUPVY LOS” alarm is raised on the local node is NOT a characteristic of an Optical Supervisory Channel Loss of Signal (OSC LOS) issue, in case that no “LD Input LOS” alarms are raised against the involved amplifiers. An “Incoming SUPVY LOS” alarm indicates that the input signal of the Optical Supervisory Channel (OSC) is lost or below the threshold6. The OSC is a bidirectional channel that connects two adjacent nodes in a DWDM network and carries OAM information and other services7. An OSC LOS issue can occur due to a fiber cut, a defective or dirty OSC fiber, or a faulty OSC transmitter or receiver8. However, if there is no “LD Input LOS” alarm raised against the involved amplifiers, it means that there is no loss of signal on the line interface of the amplifier, which carries both service channels and OSC channels9. Therefore, an “Incoming SUPVY LOS” alarm on the local node is not related to an OSC LOS issue, but rather to an OSC configuration issue or a faulty OSC card10. References : Nokia Optical Diagnostics and Troubleshooting Course | Nokia, Optical User Guide - Nokia, Alcatel-Lucent 1830 PSS-8 and PSS-16 Photonic Service Switch

The alarm masking mechanism is a feature of the 1830 PSS that prevents unnecessary alarms from being displayed on the GUI or forwarded to an external NMS when they are caused by a known fault or maintenance activity. For example, if an optical link is down due to a fiber cut, there is no need to show alarms for all the downstream interfaces that are affected by the link failure. The alarm masking mechanism hides these alarms until the root cause is resolved, and then shows them again if they persist. The alarm masking mechanism preserves the events’ original time stamps when it masks/shows alarms, so that when an alarm is not masked anymore, the user can see the original date and time associated with the issue. This helps to identify and troubleshoot problems more accurately and efficiently. References : Optical User Guide - Nokia, Alcatel-Lucent 1830 PSS-8 and PSS-16 Photonic Service Switch