100-490 Supporting Cisco Routing & Switching Network Devices (RSTECH) Questions and Answers

Theshow versioncommand on Cisco devices provides a variety of system information, including:

• Cisco IOS version:The version of the Cisco IOS software running on the device.
• Boot image:The location of the IOS image used during startup.
• Hardware information:Model, processor type, memory details.
• Interfaces:A list of the device's interfaces.
• Configuration register:The current value of the configuration register, typically displayed near the end of the output.

Why other options are incorrect:

• show flash:Displays the contents of flash memory, but not the configuration register.
• show running-config:Displays the currently active configuration, but the configuration register setting is not directly part of the running configuration.
• show config-register:This is not a standard Cisco IOS command.

When deploying Cisco Catalyst 3850 Series switches, there are two modes of operation to choose from:Install modeandBundle mode. Install mode is the default mode for the switch and uses a package-provisioning file namedpackages.confto boot the switch.It allows for a more complete set of features and requires fewer resources upon boot1. Bundle mode, on the other hand, is similar to using traditional monolithic Cisco IOS images to boot the switch.It consumes more memory than Install mode because the packages are extracted from the bundle and copied to the RAM2.Cisco recommends using Install mode for operation due to its efficiency and feature set2.

Cisco NX-OS has added support forPythonscripting to help manage user networks. Python is a powerful and versatile scripting language that is widely used for automation tasks, including network management. Cisco NX-OS leverages Python to enable networkadministrators to write custom scripts and programs that can interact with the network operating system, automate repetitive tasks, and integrate with other systems and APIs.This support for Python scripting is part of Cisco’s commitment to network programmability and automation, allowing for more efficient and flexible network operations12.

This configuration describes acrossover 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 beproperly aligned between the two devices.This is different from a straight-through cable, where the wire sequence is the same at both ends1.

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_moreSmartJacks help regenerate the signal, ensuring thatit 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.exclamationThis 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

RJ-45 is the standard connector used for Ethernet networks. Here's why it's the correct answer:

• Compatibility:Ethernet ports on both laptops and Cisco switches use RJ-45 connectors. This makes RJ-45 cables ideal for direct connections between these devices.
• Appearance:RJ-45 ports are rectangular and slightly larger than typical phone jacks (RJ-11). They have eight metal pins inside.

Why other options are incorrect:

• DVI:DVI ports are used for video connections between computers and displays.
• RJ-11:RJ-11 ports are primarily associated with analog phone lines and are smaller than RJ-45.
• DB-9:DB-9 connectors were traditionally used for serial connections on older computers and peripherals.

Thecmdprogram, also known as the Command Prompt, is the primary command-line interface in Windows. It allows you to execute various commands, including thepingcommand, to perform network testing and troubleshooting.

Here's how to usepingin the Command Prompt:

• Open the Command Prompt:Search for 'cmd' in the Windows Start Menu or use the Run dialog (Windows key + R) and type 'cmd'.
• Type thepingcommand:Enterpingfollowed by a space and then either the IP address or hostname you want to test. For instance:ping 8.8.8.8orping www.google.com.
• Press Enter:The Command Prompt will send ping requests and display the results.

Why other options are incorrect:

• Find:The Find utility in Windows is used to search for files and folders based on their content or attributes.
• Start:The Start Menu in Windows provides access to programs, settings, and power options.
• ipconfig:Theipconfigcommand is used to display network configuration information but doesn't directly execute thepingcommand.

References:

• Windows Command Prompt (cmd):https://en.wikipedia.org/wiki/Cmd.exe
• Ping command:https://en.wikipedia.org/wiki/Ping_(networking_utility)

•The label "1" points to a rectangular port on the laptop. This is consistent with the shape of a USB Type A port.

•The cable labeled "2" has an RJ-45 connector on one end and a USB Type A connector on the other end.

Electrostatic Discharge (ESD) poses a significant risk to delicate electronic components. Here's why the correct answers are essential tools for ESD protection:

• Antistatic Mat:Provides a grounded surface to work on, dissipating static buildup from your body and the components you're handling.
• ESD Wrist Strap:When connected to a grounding point (often on the antistatic mat), this strap creates an electrical path to safely discharge static electricity from your body.
• Antistatic Bag:These special bags are designed to shield sensitive components from static charge, crucial for storing and transporting electronic parts.

Why other options are incorrect:

• Negative static bag, negative static mat:These terms don't exist in standard ESD protection practices. The focus is on creating a grounded environment to neutralize static charges.
• Latex gloves:While they offer insulation, they can actually generate static electricity, increasing the risk of ESD damage.

Theipconfigcommand in Windows is used to display and manage network configuration information for the local computer. Here's what it shows:

• IP Address:The IPv4 address assigned to each network adapter.
• Subnet Mask:The subnet mask used to determine the network segment.
• Default Gateway:The IP address of the router used to send traffic to other networks.
• Other Information:DNS servers, DHCP server details, and more.

Incorrect options:

• ipconfiguration:This is not a recognized command in the Windows command prompt.
• ip configuration:This is also not a recognized command.
• ip config:While it might seem like it should work, Windows usesipconfigwithout spaces.

How to use ipconfig:

• Open the Windows command prompt (Search for 'cmd')
• Typeipconfigand press Enter.

A. Correct. SSH, or Secure Shell, is indeed a protocol that provides a secure remote access connection to network devices.It encrypts the data to ensure secure transmission over insecure networks like the internet1.

C. Correct. Telnet connections are not secure and are terminated when a router reboots.This is because Telnet does not have any mechanism to maintain the connection in case of network interruptions or device reboots1.

B, D, and E are incorrect because: B.SSH uses TCP port 22 by default, not port 23, which is used by Telnet1. D.Telnet does not provide a secure connection; it transmits data in plain text, which can be intercepted easily1. E.SSH is preferred over Telnet for security reasons because it provides encrypted connections and authentication mechanisms, which Telnet does not1.

References:=1:GeeksforGeeks - Difference between SSH and Telnet2:phoenixNAP - Telnet vs. SSH: How Is SSH Different From Telnet?3:Guru99 - Telnet vs SSH – Difference Between Them4:Difference Between - Difference Between Telnet and SSH

The correct IPv6 address notation follows the format of eight groups of four hexadecimal digits, separated by colons. The address must have exactly eight groups unless it uses the double colon (::) to represent consecutive groups of zero value. The double colon can only appear once in an address to avoid ambiguity.

Option A is incorrect because it includes a subnet mask (/128) which is not part of the actual address notation. Option B is incomplete as it does not contain enough groups and ends with a single colon. Option C has too many groups (nine instead of eight) and is therefore not a valid IPv6 address. Option D is the correct notation with eight groups of four hexadecimal digits, where necessary leading zeros are included.

References:=

• IPv6 Address Types, Notation, and Structure Explained1.
• IPv6 address formats - IBM2. =========================

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

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

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

• A. 255.255.255.255is reserved for broadcast messages to all hosts on the local network, so it cannot be assigned to a single host.
• B. 10.1.1.20falls 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. 0.0.0.0is used to denote an unknown or non-applicable target address, often used as a default route, and cannot be assigned to a host.
• D. 192.168.10.15is 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. 292.10.3.4is not a valid IPv4 address because the first octet exceeds the maximum value of 255.

References:=

• IPv4 Addressing
• Valid IP Address
• IP Address Validation

Theshow inventorycommand in Cisco IOS is designed specifically to display detailed hardware inventory information about a Cisco device. This includes:

• Component Name:The name or type of each module or card installed.
• PID (Product ID):The unique product identifier for the module.
• VID (Version ID):The version identifier for the module.
• Serial Number:The unique serial number assigned to the module.

Why other options are incorrect:

• show chassis:Some Cisco devices support ashow chassiscommand, but the information provided usually focuses on the physical chassis rather than detailed component inventory.
• show items:This is not a standard Cisco IOS command.
• show router:This command doesn't provide the level of granular hardware information thatshow inventorydoes.

When you initially log in to a Cisco router, the default operating mode is user EXEC mode. This mode provides a limited set of basic monitoring commands but does not allow for any configuration changes to the router’s settings. To make configuration changes, you must enter privileged EXEC mode (often accessed by the enable command), which offers a wider range of commands that allow for the viewing and modification of the configurationGlobal configuration mode is accessed from privileged EXEC mode to modify the router’s configuration, and ROM monitor mode is a low-level mode used mainly for recovery purposes1.