Cisco 100-490 Supporting Cisco Routing & Switching Network Devices (RSTECH) Exam Practice Test

The Cisco Nexus 9300 Series switches are a family of high-performance data center switching products. However, only a specific subset of models within this series supports 400-Gbps Ethernet ports.

Based on the information available online, two models from the Cisco Nexus 9300 Series that offer 400-Gbps Ethernet ports are:

Cisco Nexus 9316D-GX: This is a 1RU fixed switch that provides 16 ports of 400 Gbps (QSFP-DD) with a non-blocking switch architecture. It's suitable for aggregation, core, or spine applications.

Cisco Nexus 93600CD-GX: This is also a 1RU fixed switch, but it offers a combination of ports. It includes 28 ports of 100G and 8 ports of 400 Gbps (QSFP-DD) with a non-blocking switch architecture. This model is well-suited for data center Top-of-Rack (ToR), End-of-Row (EoR), and collapsed aggregation and access deployments, particularly when used with Cisco Nexus 2000 Fabric Extenders.

References:

Cisco Nexus 9000 Series 400G Deployment Guide

The Xmodem option that enhances error checking when copying an image to flash memory is the -e option. This option enables error checking to ensure the integrity of the file being transferred. Xmodem is a protocol that uses checksums or cyclic redundancy checks (CRC) to detect errors during the transfer. The -e option specifically invokes CRC error checking, which is more reliable than the basic checksum method, providing an additional layer of verification that the copied image is free from errors. References := The information is based on standard practices for using the Xmodem protocol for file transfers in networking devices, as outlined in Cisco’s documentation and support forums1.

Straight-through cables are the most common type of Ethernet cable. They're used to connect dissimilar devices, such as a laptop to a router or a switch to a router. The internal wiring of the cable connects the transmit pins on one end to the receive pins on the other end, and vice versa.

Crossover cables were historically necessary to connect similar devices (e.g., router to router, or switch to switch). Modern devices often have auto MDI-X capabilities, allowing them to automatically detect and adjust to straight-through or crossover connections as needed.

Rollover cables have a reversed pinout and are primarily used for console access into Cisco routers and switches.

Fiber cables use fiber optic technology for high-speed, long-distance connectivity.

References:

Cisco Networking Academy: Introduction to Networks Course

Rollover cables are specifically designed for connecting to the console ports on Cisco routers and switches. Here's why they are the right choice:

Pinout: Rollover cables have a reversed pinout compared to standard Ethernet cables. This matches the console port's wiring, allowing for configuration access.

Appearance: Rollover cables are often light blue in color to help distinguish them from standard Ethernet cables.

USB Adapter: Many modern laptops may not have a direct serial port. In this case, a rollover cable with a USB-to-serial adapter is used.

Why other options are incorrect:

Straight-through: Used for connecting unlike devices (e.g., switch to computer). They won't have the correct wiring for console connections.

Fiber: Used for high-speed, long-distance networks. Console ports use a serial-based connection, not fiber optics.

Crossover: Used to connect similar devices (e.g., switch to switch). The pinout is not the same as what a console port requires.

The fastest way to recover a software version on a Cisco device that supports a USB flash port is by using the copy command with USB memory. This method allows for the direct transfer of the Cisco IOS image from a USB flash drive to the device’s memory. It is significantly faster than using TFTP or Xmodem, which are slower due to network speed limitations and the inherent slowness of the Xmodem protocol, respectively. By using a USB flash drive, you can bypass these limitations and achieve a quicker recovery process

While the initial answers focused on the most common causes, here's why the other options could also contribute to an interface being stuck in the "up/down" state:

A. Speed or Duplex Mismatch: Devices on either end of an Ethernet connection need to use compatible speed (e.g., 100 Mbps, 1 Gbps) and duplex (full-duplex or half-duplex) settings. Mismatches can prevent the line protocol from coming up even if the physical link is established.

B. Layer 2 Mismatch in Encapsulation Type: Some protocols used on Ethernet networks, like ISL and 802.1Q, have specific encapsulation requirements. If devices on each end aren't using the same encapsulation type, the line protocol will likely remain down.

C. The Ethernet Interface Has Been Manually Disabled: Correct! Administrators can put an interface in a shutdown state using commands like shutdown. This brings down the line protocol even if the physical connection is good.

D. Keepalives Are Not Being Received by the Local Device: While less likely to be the sole cause, issues with keepalive mechanisms used in some routing protocols could potentially lead to the line protocol going down. If the local device expects keepalives and doesn't receive them, it might assume a connectivity problem and affect the interface status.

E. The Ethernet Cable Might Not Be Attached Properly: While a disconnected or faulty cable would usually make the interface down/down, it's possible in some scenarios for a partially connected or damaged cable to result in a link being detected (Layer 1 up) but with errors preventing the line protocol (Layer 2) from initializing.

Troubleshooting network issues often involves considering multiple factors and testing different possibilities. The "up/down" status gives important clues but might have several potential root causes.

The features associated with single-mode fiber-optic cable include:

Consists of a single strand of glass fiber: Single-mode fiber uses a single core (strand) of glass fiber to transmit light signals. This core is thinner than that of multimode fiber, allowing for greater transmission distances.

Carries a higher bandwidth than multimode fiber: Single-mode fiber can carry higher data rates over longer distances compared to multimode fiber. It is commonly used in long-haul communication links and high-speed networks.

References:

Single-mode vs. Multimode Fiber

Fiber Optic Cable Types

This configuration describes a crossover cable. A crossover cable is used to connect two similar devices directly, such as two computers or two switches, without the need for an intermediate device like a router. The wires at one end of a crossover cable are in reverse sequence to the wires at the other end, which allows the transmit and receive signals to be properly aligned between the two devices. This is different from a straight-through cable, where the wire sequence is the same at both ends1.

The Cisco Nexus 3432D-S and Cisco Nexus 3408-S are part of the Cisco Nexus 3400 Series switches that support 400-Gbps Ethernet ports. The Cisco Nexus 3432D-S is designed with 32 ports of 400G, providing high-density and high-throughput capabilities1. The Cisco Nexus 3408-S offers flexibility with 100G or 400G Line-Card Expansion Modules (LEMs), allowing for configurations with 32 ports of 400G2. These switches are engineered for data centers requiring high performance, low latency, and power efficiency, with the Cisco Nexus 3432D-S offering industry-leading performance-per-watt power efficiency at low latency1.

SmartJacks are specialized devices used in telecommunications, particularly for T1/E1 lines. Here's why the correct answers make sense:

Signal Conversion: SmartJacks can convert between different signaling types (e.g., AMI to B8ZS). This is necessary because different telecommunication lines may use varying signaling standards.exclamation

Signal Regeneration: As signals travel over long distances, they can weaken and degrade.expand_more SmartJacks help regenerate the signal, ensuring that it maintains its strength and integrity throughout the transmission.expand_more

Why other options are incorrect:

Concentration point: SmartJacks are not primarily used as concentration points for dial-in/out connections.exclamation This function is typically handled by modems or other specialized devices.exclamation

Layer 2 operation: SmartJacks primarily operate at Layer 1 (Physical Layer) of the OSI model, focusing on the physical transmission of signals.

Channel Testing: While some SmartJacks may offer some basic channel testing capabilities, their primary functions are signal conversion and regeneration.

References:

SmartJack (Wikipedia): https://en.wikipedia.org/wiki/Smartjack

The image provided shows a networking device connected to a laptop via a console cable. Based on the visual indicators and standard port designs:

C. 3 is a USB 5-pin mini USB Type B port: The port labeled “3” on the laptop is smaller than a standard USB Type A port, which suggests it is a mini USB Type B port, commonly used for connecting to networking devices for console access.

E. 2 is a USB 5-pin mini USB Type B to USB Type A console cable: The cable labeled “2” has one end that fits into the mini USB Type B port on the laptop (as identified in point 1), and the other end, which is not clearly visible in the image, is inferred to be a USB Type A connector that would typically connect to a computer’s USB port.

Ethernet

The typical physical connector used for a Gigabit Ethernet port is an RJ-45. This connector is standard for network cabling and provides the necessary performance for Gigabit Ethernet, which is also known as 1000BASE-T. RJ-45 connectors are used because they can support higher data rates compared to other connectors like RJ-11 or RJ-9, which are commonly used for telephone connections, and DB-25, which is an older serial port connector not suitable for high-speed Ethernet connections1.

References :=2: Ethernet Alliance - The Physical Layer of Ethernet 3: Altium - Gigabit Ethernet 101: Basics to Implementation 1: Ascent Optics - All You Need to Know About RJ45 Cables: Connectors, Interfaces, and… 4: Hardware Secrets - Gigabit Ethernet and How it works (a 2022 Guide)

The command that returns the user to the main configuration prompt from the interface configuration prompt is exit. When you are in interface configuration mode on a Cisco device and you want to return to the global configuration mode, you use the exit command. If you want to go all the way back to privileged EXEC mode, you would use the end command or press Ctrl-Z1.

The configuration register on Cisco devices is a 16-bit value, typically represented in hexadecimal notation (e.g., 0x2102). The lowest four bits (bits 0-3) of this value are designated as the boot field.

The Boot Field's Importance:

The boot field determines how the device will load its operating system (Cisco IOS) during the startup process. Here's a basic breakdown of common boot field values:

0x0: Stay at the ROMmon prompt.

0x1: Boot from ROM (often used for troubleshooting or recovery).

0x2 - 0xF: Load the operating system based on settings in the startup configuration (NVRAM) or from a network server if specified.

Example:

A configuration register value of 0x2102 indicates that the boot field is 0x2 (the last digit). This is a common default setting, instructing the device to load the Cisco IOS image from Flash memory.

References:

Cisco Configuration Register Detailed Explanation: [invalid URL removed]

Configuration Register Settings (Cisco): https://networklessons.com/cisco/ccna-routing-switching-icnd1-100-105/configuration-register-cisco-ios

The command show file system is used on Cisco devices to display a list of all the file systems available. This command provides information about each file system, including its name, size, free space, and file system type (such as flash or nvram). It’s a useful command for network administrators to manage and navigate through different storage areas on Cisco devices, ensuring they can access and maintain the device’s file structure effectively. References := File System Commands on Cisco IOS XR Software - Cisco, Working with the Cisco IOS File System, Configuration Files, and Software Images

The show ip interface brief command provides a concise summary of the status and IP addressing configuration of interfaces on a Cisco router or switch. Here's what it displays:

Interface: The name of the interface (e.g., FastEthernet0/0, GigabitEthernet1/1).

IP Address: The Layer 3 IP address assigned to the interface (if any).

OK? Indicates the IP layer status of the interface (YES if operational, NO if not).

Method: How the IP address was configured (manual or DHCP).

Status: The Layer 1 status of the interface (up or down).

Protocol: The Layer 2 status of the interface (up or down).

Why other options are incorrect:

Layer 2 address: The show ip interface brief command does not directly display Layer 2 (MAC) addresses. You can use the show interface command for that.

Keepalive: Keepalives are used in some routing protocols but are not generally reflected in the output of the show ip interface brief command.

Encapsulation type: Encapsulation information is also not typically included in the show ip interface brief output.

References:

Cisco IOS show ip interface brief command: [invalid URL removed]

Example output of show ip interface brief: https://www.cisco.com/E-Learning/bulk/public/tac/cim/cib/using_cisco_ios_software/cmdrefs/show_ip_interface.

The ping command is specifically designed to test network connectivity and reachability. Here's how it works:

Echo Request: The ping command sends an ICMP (Internet Control Message Protocol) Echo Request packet to a specified destination IP address or hostname.

Echo Response: If the target host is reachable, it will respond with an ICMP Echo Reply packet.

Analysis: The ping command measures the round-trip time (RTT) between the source and destination. It also reports statistics like packet loss and response times.

Why other options are incorrect:

echo: In some command-line environments, the echo command is used to display text on the screen and does not relate to network testing.

access: This is a general term and does not refer to a specific command for sending echo requests.

connect: Some tools use the connect command to establish a TCP connection to a remote host, but it doesn't directly utilize ICMP echo packets like the ping command.

References:

ping (Wikipedia): https://en.wikipedia.org/wiki/Ping_(networking_utility)

 The decompressed form of Cisco IOS Software and the running configuration are stored in DRAM (Dynamic Random-Access Memory) on Cisco devices. DRAM is used as the main memory for the device, where the operating system runs and the running configuration is stored. When a Cisco device boots up, the IOS image is decompressed and loaded into DRAM, and the running configuration is also held in this memory type. It’s important to note that DRAM is volatile memory, which means its contents are lost when the device is powered off or restarted12. References := Maintaining System Memory Configuration Guide, Cisco IOS Release 15M&T - Cisco, Types of memory on a Cisco device - Study-CCNA

IPv4 addresses consist of four octets, each ranging from 0 to 255. The addresses are used to uniquely identify devices on a network.

A. 255.255.255.255 is reserved for broadcast messages to all hosts on the local network, so it cannot be assigned to a single host.

B. 10.1.1.20 falls within the range of private IP addresses (10.0.0.0 to 10.255.255.255) and can be assigned to a host within a private network.

C. 0.0.0.0 is used to denote an unknown or non-applicable target address, often used as a default route, and cannot be assigned to a host.

D. 192.168.10.15 is also within the range of private IP addresses (192.168.0.0 to 192.168.255.255) and can be assigned to a host within a private network.

E. 292.10.3.4 is not a valid IPv4 address because the first octet exceeds the maximum value of 255.

References :=

IPv4 Addressing

Valid IP Address

IP Address Validation

A DTE (Data Terminal Equipment) device is an end instrument that converts user information into signals or reconverts received signals. In the context of networking, a router can be considered a DTE device because it is typically at the user end of a user-network interface and serves as a data source or destination. It communicates with the data circuit-terminating equipment (DCE), such as a modem, to send and receive data across the network345.

References := Wikipedia, Techopedia, Network Encyclopedia

A Wide Area Network (WAN) connection typically involves several components that work together to enable data communication over large distances. Two key components of a WAN connection are:

CSU/DSU (Channel Service Unit/Data Service Unit): This device acts as a gateway between the local area network (LAN) and the WAN. It converts the digital signals used in the LAN to the signals used in the WAN, which are often analog12.

Router: A router is used to connect multiple networks together and direct data traffic. In the context of a WAN, routers are responsible for determining the best path for data to travel across the network12.

References := Spiceworks, Cisco