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

The data link layer of the OSI model, which is Layer 2, defines how data is formatted for transmission and controls access to the physical media. This layer is responsible for the node-to-node delivery of data and handles error detection and correction from the physical layer. It also manages the way data packets are sent over the network, including the framing, addressing, and flow control. The data link layer ensures that messages are delivered to the proper device on a LAN using hardware addresses (MAC addresses) and translates messages from the network layer into bits for the physical layer to transmit

TFTP, or Trivial File Transfer Protocol, is a simple protocol used for transferring files. Unlike other file transfer protocols, TFTP operates on top of the User Datagram Protocol (UDP), which is a connectionless protocol. This means that TFTP does not establish a persistent connection between the client and server, and it does not guarantee reliable delivery of packets, error checking, or correction. TFTP is typically used in scenarios where simplicity and minimal memory footprint are more critical than the need for reliable delivery, such as when booting a device over a network123. References := Wikipedia, GeeksforGeeks, PyNet Labs

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. 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 Telnet 2: phoenixNAP - Telnet vs. SSH: How Is SSH Different From Telnet? 3: Guru99 - Telnet vs SSH – Difference Between Them 4: Difference Between - Difference Between Telnet and SSH

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

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. =========================

Loopback plugs are used to test the physical connections and configurations of network equipment. In a 56K modem loopback plug, the following pins are looped to create a test signal:

Pins 1 and 7 (Transmit): Looping the transmit pins back to each other allows the device to test its own signal transmission.

Pins 2 and 8 (Receive): Looping the receive pins back to each other allows the device to test its ability to receive its own signal.

Understanding RJ-45 Wiring:

RJ-45 connectors are standardized and have a specific pinout for various applications like Ethernet networking and analog telephony connections. You can find resources online that show the standard RJ-45 color coding and pin assignments.

The show environment command in Cisco devices is used to display the status of the system’s environment, including power supplies and sensor temperatures. This command provides a comprehensive overview of the environmental conditions affecting the device, such as temperature readings and power supply status.

Option A, show hardware, is not specific to power supplies and sensor temperatures. Option B, show module, displays information about the network modules installed in the device but not the environmental conditions. Option D, show diag, is used for diagnostic purposes and does not specifically provide the status of power supplies and sensor temperatures.

Therefore, the correct answer is C, show environment, which is the command that specifically shows the status of power supplies and sensor temperatures in Cisco devices12.

References :=

Cisco Community discussions on power supply details1.

Cisco documentation on Environmental Monitoring and Power Management2.

A standard UTP (Unshielded Twisted Pair) cable contains 4 pairs of copper wires, which are twisted together to help cancel out electromagnetic interference and support data transmission across various networking and telecommunications applications1. Each pair consists of two individual copper cables twisted around each othe

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

Questions no: 12 Verified Answer: = B. switch-to-router, E. switch-to-server Comprehensive and Detailed Step by Step Explanation: = RJ-45 straight-through cables are used to connect different types of devices in a network. The standard practice is to use straight-through cables for connections that are unlike to each other, such as:

Switch-to-Router: A switch connects devices within a network by using MAC addresses to forward data to the correct destination. A router, on the other hand, connects multiple networks and uses IP addresses to determine the best path for the data packets. Connecting a switch to a router requires a straight-through cable because they are different types of devices12.

Switch-to-Server: Servers are the powerful computers that provide resources, data, services, or programs to the client machines in the network. When connecting a switch to a server, a straight-through cable is used because the switch and the server are different types of devices with different functions within the network12.

References := Guru99, TheTechMentor

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)

In the context of IPv4 addresses, a host address is an identifier for a specific device on a network. The addresses 10.1.1.20 and 192.168.10.15 are both within ranges typically reserved for private networks, making them suitable for assignment to host computers within a local network. Address 292.10.3.4 is not a valid IPv4 address because the first octet is beyond the maximum value of 255. Address 255.255.255.255 is reserved for broadcast messages to all hosts on the local network, and 0.0.0.0 is used to denote an unspecified address, often indicating the absence of an IP address123. References := IP address, Network address, and Host address Explained, IP address - Wikipedia, Understanding IP Addresses: How IP Addressing Works | ENP

•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.

Microsoft Notepad is the preferred text editor for working with Cisco configuration files and other simple text documents for several reasons:

Plain Text Focus: Notepad is designed specifically for plain text editing. It does not add any formatting, hidden characters, or metadata that could interfere with the configuration file's structure.

Cisco Syntax Compatibility: Cisco configurations rely on specific syntax and spacing. Notepad preserves these elements accurately.

Universality: Notepad is a basic text editor included in all versions of Windows, ensuring accessibility and eliminating the need for additional software.

Why other options are not ideal:

Microsoft Word: Word is a word processor and includes formatting, fonts, and other features that are not compatible with Cisco configuration files. This formatting can corrupt the configuration.

Microsoft Access: Access is a database management system, not suited for text file editing.

Microsoft Excel: Excel is a spreadsheet application and adds its own structure and formatting that conflicts with configuration file formats.

USB thumb drives (also called flash drives) serve several practical purposes in networking:

File Transfer: They are excellent for transferring Cisco router or switch configuration files between the device and a PC. This allows you to back up configurations, easily restore configurations, or work with them offline.

IOS Image Storage: USB thumb drives are convenient for storing and transferring Cisco IOS images, especially when you need to upgrade or recover network devices.

Why other options are incorrect:

to save the system log: While you might temporarily store log files on a USB drive, routers and switches generally utilize internal memory or a remote syslog server for logging purposes.

to save router hardware information: Hardware inventory information obtained from commands like show inventory is often copied and pasted to text files, which can then be stored on a USB drive. However, the drive itself doesn't directly save or store this hardware information.

to increase system memory: USB drives are not designed to act as additional system memory (RAM) for a router or switch.

An RJ-45 56K loopback plug is used to test the functionality of network ports, particularly for T1/56K lines. The correct loopback wiring for such a plug involves looping pins 1 and 4, as well as pins 2 and 5. This configuration allows the device to send and receive signals on the same wire pairs, effectively testing the transmit and receive paths of the port1.

References := Loopback Tests for T1/56K Lines - Cisco

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.