800-150 Supporting Cisco Devices for Field Technicians (FLDTEC) Question and Answers

NVRAM → Startup configuration

RAM → Running configuration

ROM → Bootstrap code, POST code, ROM monitor

Flash memory → Cisco IOS software, backup configuration

Each memory type in a Cisco device serves a specific function in the boot process and runtime operation. NVRAM retains configuration across reboots, RAM is volatile and holds active configs, ROM handles initial boot tasks, and flash stores the operating system.

This content is covered thoroughly in"Cisco Equipment and Related Hardware"in the FLDTEC curriculum. Here's the breakdown:

ROM (Read-Only Memory)

Stores bootstrap code, POST (Power-On Self-Test), and ROM Monitor.

These are essential for the device’s initial power-on operations and recovery modes.

NVRAM (Non-Volatile RAM)

Holds thestartup configuration file, which is loaded during the boot process.

Content remains intact after a reboot or power cycle.

RAM (Random Access Memory)

Stores therunning configurationand current operational state of the router or switch.

Also used for routing tables, ARPcache, and packet buffers.

Data is lost when the device is powered off or rebooted.

Flash Memory

Contains theCisco IOS image, system files, and can storebackup configurations.

It is a non-volatile storage, so it retains data after reboots.

Within theFLDTECtraining, especially underMaintenance and RMA Procedures, there is a strong emphasis on safely transferring and adapting configurations from failed or decommissioned devices to replacement units.

The official guidance includes the following:

"When reusing a configuration from an old device, make sure to retain the necessary security elements such as username entries. This ensures the replacement device is still accessible under the correct user credentials."

Here's a breakdown of why the correct answer isB:

A. Remove all configurations under line vty 0 4:This would eliminate remote access settings, making it harder to manage the device.

B. Retain all username entries:Correct. Keeping the username entries ensures continued secure access and avoids loss of administrative control.

C. Keep all access-list commands intact:Not always required — ACLs are often tailored to interface-specific settings or environments which may differ between devices.

D. Add the enable password cisco command:Not a best practice. Default passwords (like cisco) should be avoided for security reasons, and it's not required if enable secret is already in use.

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Kickstart Image→ Specialized bootloader that initializes the hardware

System Image→ Contains the full NX-OS kernel and operating system

Global configuration command mode→ Provides access to the broadest range of commands that affect the device as a whole

EXEC command mode→ Allows for displaying device status and configuration information

This knowledge is covered underCisco IOS/NX-OS Software Basicsin the FLDTEC training:

Kickstart Image:Alightweight bootloader image that initializes hardware and launches the system image. It's comparable to ROMMON in traditional IOS devices.

System Image:Includes the full NX-OS operating system, services, drivers, and kernel required to run the device.

Global Configuration Mode:After entering privileged EXEC mode (enable), this mode allows changes to system-wide settings such as interfaces, routing protocols, and VLANs.

EXEC Mode:Has two levels—User EXECandPrivileged EXEC. User EXEC provides limited diagnostic commands, while Privileged EXEC allows more extensive system views (show commands, reload, etc.).

Understanding these layers is essential when maintaining or restoring NX-OS devices in field environments.

In an enterprise network,Virtual Local Area Networks (VLANs)are the key Layer 2 technology used to logically segment a network into multiple broadcast domains. VLANs allow network administrators to assign individual switch ports to specific VLANs, enabling effective network segmentation and traffic management.

This configuration extends to access layer devices, such as switches where end-user devices connect. By isolating traffic into VLANs, administrators can improve network performance, enhance security by separating sensitive departments (such as finance and HR), and simplify network management.

Unlike routing protocols such as BGP and OSPF, which operate at Layer 3, or MPLS, which is a Layer 2.5 forwarding technology used primarily in service provider networks, VLANs are explicitly designed for Layer 2 segmentation within LAN environments.

In wireless networking, theBasic Service Area (BSA)refers to the physical area of radio frequency coverage provided by an access point (AP) in a Basic Service Set (BSS). The BSA defines the coverage area where wireless clients can connect to the network through the AP. The size and shape of a BSA depend on various factors, including the AP's transmit power, antenna type, and physical environment.​

Option A, the Service Set Identifier (SSID), is the network name broadcast by the AP. Option C, Wireless LAN (WLAN), refers to the overall wireless network. Option D, Wireless LAN Controller (WLC), is a device that manages multiple APs in a network.​

Cloud-based managementis a core feature of Cisco Merakiswitches and significantly simplifies the device replacement process. When a failed switch is replaced:

The new hardware can be claimed in the Meraki dashboard.

The previously assigned configuration is automatically applied to the replacement device.

This eliminates the need for local reconfiguration and ensures continuity with minimal manual effort.

This centralized approach ensures that configurations are stored securely and consistently applied across devices.

The Data Link Layer (Layer 2) of the OSI model is responsible for node-to-node data transfer and plays a crucial role in error detection and media access control. It ensures that data frames are transmitted to the correct device on a local network segment.​

This layer is divided into two sublayers:​

Logical Link Control (LLC):Manages frame synchronization, flow control, and error checking.

Media Access Control (MAC):Controls how devices on the network gain access to the medium and permission to transmit data.

Together, these sublayers ensure reliable data transmission by detecting and possibly correcting errors that may occur in the Physical Layer. They also manage how devices share the transmission medium, preventing collisions and ensuring orderly communication.​

Cisco MDS switches are segmented into two key categories: Director-Class and Fabric Switches, each tailored for different SANenvironments:

Director-Class Switches (e.g., Cisco MDS 9700 Series):

Modular and highly scalable

Support hot-swappable components (line cards, supervisors, fabric modules)

High port density and performance for core SANs in enterprise data centers

Fabric Switches (e.g., Cisco MDS 9148T):

Compact, fixed-form factor

Best suited for smaller SANs or edge locations

Cost-effective and simple to deploy

This distinction is important when selecting hardware for data center core vs access layers in SAN architectures.

In a Cisco Nexus switch withdual power supplies, the recommended method is toconnect each power supply to a separate power source(Option C). This ensures power redundancy and fault tolerance.

If one power source fails (e.g., due to a power outage or circuit failure), the switch can continue operating uninterrupted using the second power source. Connecting both to a single source (Option D) defeats the purpose of redundancy.

This procedure is taught in theFLDTEC courseunder theDevice Configuration and Verificationsection and reflects standard field technician workflows:

Connect to the console portusing a console cable and terminal software (like PuTTY or Tera Term).

Access the CLIof the Cisco device by logging in via the console session.

Create a log fileor enable logging in the terminal emulator to begin capturing output.

Check the router statususing commands such as show running-config, show ip interface brief, or show version.

Save the output filefrom the terminal emulator for documentation, troubleshooting, or escalation.

This logical flow ensures accurate diagnostics and traceability during field support operations.

When configuring a network port for a newly installed IP phone, two critical parameters to ensure optimal performance are:​

VLAN Assignment:Assigning the correct VLANs is essential for segregating voice and data traffic. Typically, a separate voice VLAN is configured to prioritize voice traffic and enhance security.​

Power over Ethernet (PoE):PoE allows the switch to supply power to the IP phone over the same Ethernet cable used for data transmission. This eliminates the need for separate power supplies and simplifies installation.​

While QoS classification (Option E) is important for prioritizing voice traffic, it is typically configured at a broader network level. Link aggregation (Option B) and Spanning Tree Protocol (Option C) are more relevant to network redundancy and loop prevention, respectively, and are not directly critical for the initial configuration of an IP phone port.​

Theboot systemcommand is used in globalconfiguration mode to specify the source and filename of the Cisco IOS software image that should be loaded during the device’s boot process. This command ensures that the device loads a specific IOS image, whether it's stored locally in flash or fetched from a TFTP server.

Syntax example:

boot system flash:c1900-universalk9-mz.SPA.157-3.M3.bin

boot image,boot ios, andboot sourceare invalid or non-existent in standard Cisco IOS.

The highlighted component on the Cisco I/O module is the chassisconnections LED, which indicates the status of connectivity between the I/O module and the chassis.

In the exhibit, the orange arrow points to asmall rectangular LED indicatorlocated to the left side of the I/O module (Cisco UCS-IOM-2304). This specific LED isnot aligned with the ports, fans, or screws, which helps identify it correctly.

Chassis connections LED (B)is responsible for indicating thestatus of uplink/downlink communicationbetween the I/O module and the chassis.

Greenusually indicates a healthy link.

Amberoroffmay indicate a problem or no connection.

Why the other answers are incorrect:

A. Captive screw→ These are at the far corners, not where the arrow points.

C. Fan module LED→ This IOM doesn’t have user-visible fan LEDs atthe front face.

D. Fixed port→ These are the large rectangular SFP ports clearly visible in the middle, not near the arrow.

This identification is important whentroubleshooting chassis-to-IOM connectivityor verifyingmodule status LEDsduring field maintenance.

To ensure asmooth replacementof a Cisco UCS C-Series Rack-Mount Server, two critical actions are:

Back up the server configuration using the Cisco Integrated Management Controller (CIMC): This preserves all configuration data such as BIOS settings, RAID setup, and network configuration. After replacing the hardware, this configuration can be restored to minimize setup time.

Decommission the server if it is integrated in a Cisco UCS domain: Before physically replacing the server, decommissioning it ensures the UCS Manager properly releases it from the inventory, preventing configuration conflicts or orphaned profiles.

Other options, like reconfiguring DHCP or disabling firewalls, are not required procedures for a UCS C-Series hardware swap.

When addressing call quality issues between IP phones, theReal-time Transport Protocol (RTP)is the primary protocol to analyze. RTP is responsible for the actual transmission of voice data during a call, and its performance directly impacts call quality.​

Key factors affecting RTP and, consequently, call quality include:​

Packet Loss:Missing packets can lead to audio gaps.

Jitter:Variations in packet arrival times can cause choppy audio.

Latency:Delays in packet delivery can result in noticeable lag.​

Analyzing RTP streams allows technicians to identify these issues and implement appropriate Quality of Service (QoS) measures to mitigate them.​

Incontrast:​

SIP (Session Initiation Protocol):Handles call setup, modification, and teardown but not the media stream.

SCCP (Skinny Client Control Protocol):A Cisco proprietary protocol for signaling, not media transport.

H.323:An older protocolsuite for multimedia communication, encompassing both signaling and media, but less commonly used in modern IP telephony.​Reference:Supporting Cisco Devices for Field Technicians (FLDTEC) – Troubleshooting Methodologie

Right-To-Use (RTU) licensesare locally managed licenses that allow users to activate specific features on Cisco devices without the need for external tools or connectivity to Cisco's licensing infrastructure. These licenses operate on an honor-based system, where the user agrees to comply with the licensing terms without mandatory enforcement mechanisms.​

In contrast:​

Hybrid licensescombine aspects of traditional and smart licensing models.

PAK (Product Authorization Key) licensesrequire registration and activation through Cisco's licensing portal.

Smart licensesnecessitate communication with Cisco's Smart Licensing servers for activation and management.​

Theshow interface statuscommand offers a succinct overview of switch port characteristics, including:​

Port ID

VLAN assignment

Duplex mode

Speed

Media type​

This command is particularly useful for quickly assessing theoperational status and configuration of switch ports, aiding in troubleshooting and verification tasks.​

In contrast:​

show cdp neighborsdisplays information about directly connected Cisco devices.

show controllersprovides low-level hardware information.

show ip interface briefoffers a summary of IP-related interface information.​

In a local area network (LAN), the primary function of aswitch is to operate at Layer 2 (Data Link Layer) of the OSI model. Switches use MAC addresses to forward frames to the appropriate destination ports. This targeted forwarding mechanism divides the network into separate collision domains for each switch port. By isolating collision domains, switches significantly reduce the chance of collisions, enhancing the performance and efficiency of the network.

Unlike hubs, which forward all traffic to all ports (thus creating a single collision domain), switches intelligently forward only the necessary traffic to the correct port. This capability allows multiple simultaneous conversations on different switch ports without interference.

Routers, which operate at Layer 3 (Network Layer), are used to route packets between different networks, not within the same LAN. Wireless connectivity is provided by wireless access points (WAPs), not switches. Encryption is typically handled by security protocols or devices such as firewalls and not by switches directly.

TheSpine-and-Leafarchitecture is the preferredpod-based deployment modelin modern data centers because of itshigh scalability and flexibility. In this topology:

Leaf switchesconnect to servers and act as the access layer.

Spine switchesfunction as the core layer, interconnecting all leaf switches.

This non-blocking, highly redundant model supportspredictable latency, easy horizontal scaling, and load balancing, making it ideal for cloud-scale and virtualized environments.

Top of Rack (ToR)andEnd of Row (EoR)are physical cabling layouts that do not inherently provide the same level of architectural scalability.

Fabric Extender modelsextend switch ports but depend on upstream switches for intelligence, limiting flexibility.

Acrossover UTP (Unshielded Twisted Pair) cableis used to connect two similar devices directly. This includes:​

Switch to switch

Router to router

PC to PC​

The crossover cable reverses the transmit and receive pairs, allowing for proper communication between like devices without the need for an intermediary device.​

Conversely, astraight-through cableis used to connect dissimilar devices, such as:​

PC to switch

Router to switch

PC to router​

This cable maintains the same wiring on both ends, suitable for connecting different types of devices.​

Therefore, when connecting electrically like devices, a crossover cable is appropriate.​

During the boot process of Cisco devices runningNX-OS, pressingCtrl-Cat the right time will interrupt the boot sequence and bring the system to theboot loader or ROMmon mode(commonly referred to as the boot prompt).

This allows a technician to perform low-level operations such as recovering passwords, specifying an alternate boot image, or performing diagnostics.

Other options (Ctrl-X, Ctrl-Z, Ctrl-1) are not used for interrupting the boot process in Cisco NX-OS platforms.

The commandcopy tftp: running-configis used to retrieve a configuration file from a TFTP server and merge it with the current running configuration of a Cisco device. Thisoperation is additive, meaning it integrates the new configuration commands into the existing running configuration without removing any pre-existing commands unless explicitly overridden.​

This method is particularly useful when restoring configurations to a replacement device, as it allows for the seamless integration of necessary settings without disrupting the current operational state.​

In contrast, usingcopy tftp: startup-configwould overwrite the startup configuration file, which could lead to unintended consequences upon the next device reload. The optionsload tftp: running-configandmerge tftp: running-configare not valid Cisco IOS commands.​

When connectingtwo devices of the same type(e.g., two routers, two switches, or two DTEs), acrossover cableis required. This cable swaps the transmit and receive pairs to allow direct communication between devices without the need for an intermediate device like a switch.

Straight-through cablesare used to connect different types of devices (e.g., PC to switch).

Rolled cablesare used for console access.

USB Type A to Bcables are typically used for peripheral device connections, not networking.

In theFLDTEC course, underSafety and ESD Procedures, Cisco outlines the following safety workflow before working on any network hardware:

Locate Emergency Power-Off Switch: Identifying how to cut power quickly is essential in case of an electrical fault or emergency.

Disconnect Power: Always ensure the power source is turned off and disconnected before handling any components.

Verify with Multimeter: Use a multimeter to confirm that no voltage is present before proceeding.

Connect ESD Strap: Once confirmed safe, attach your ESD strap to a grounded point to prevent electrostatic damage to sensitive components.

Following this process is critical not only forpersonal safetybut also forequipment protection, especially duringhardware installation, maintenance, or RMA replacements.

During password recovery on Cisco devices, the configuration register is modified to instruct the device to bypass the startup configuration stored in NVRAM. This allows administrators to access the device without being prompted for existing passwords. The standard procedure involves changing the configuration register value to0x2142, which tells the device to ignore the startup configuration during the next boot. Once access is gained, the administrator can reset passwords and then restore the original configuration by resetting the configuration register to its default value, typically0x2102.​

Component to configure→ interface

Interface type→ FastEthernet

Port→ 1

Slot→ 0

This command structure is part of theDevice Configuration and Verificationsection in the FLDTEC course. It teaches how to navigate and configure interfaces on Ciscodevices using the IOS CLI:

interface is the global configuration mode command to begin configuring a network interface.

FastEthernet specifies thetype of interface(could also be GigabitEthernet, Serial, etc.).

0/1 represents theslot/portstructure used on Cisco devices:

The first digit (before the slash) is theslot number.

The second digit (after the slash) is theport numberwithin that slot.

This structure allows Cisco to modularly address interfaces, especially in devices with multiple slots or module-based configurations.

Theserial numberfor Cisco switches is typically found on a label located on therear panel near the power supplies. This positioning allows technicians to quickly access identification information even when the device is not powered on.

This label is essential for inventory tracking, RMA procedures, and registration for support. Serial numbers are not typically placed on the top or bottom surfaces for devices mounted in a rack, as those areas are less accessible.