Cisco 100-490 Exam Dumps & Practice Test Questions

Question 1:

Which transport protocol is primarily used by the Trivial File Transfer Protocol (TFTP)?

A. RSVP
B. TCP
C. HTTP
D. UDP

Correct Answer: D

Explanation:

TFTP, or Trivial File Transfer Protocol, is a lightweight protocol designed for simple file transfers, typically used in scenarios such as transferring configuration files to network devices or boot files to diskless workstations. Unlike more complex file transfer protocols, TFTP was built with minimal functionality to support ease of implementation and low resource consumption. This makes its choice of transport protocol particularly important.

A. RSVP is a signaling protocol used to reserve resources across an IP network. It’s employed for Quality of Service (QoS) purposes in multimedia streaming and voice applications, but it has no role in data transport for file transfers. Thus, TFTP does not use RSVP.

B. TCP (Transmission Control Protocol) is a reliable, connection-oriented protocol commonly used by FTP, HTTP, and email. It provides error correction, packet sequencing, and acknowledgment of data delivery. However, TFTP intentionally avoids this overhead to maintain its simplicity. Using TCP would negate the lightweight benefits TFTP aims to offer.

C. HTTP is used to serve web pages and transfer hypermedia over the internet. It is layered over TCP and provides reliable file transfer capabilities, but again, this reliability and complexity are beyond TFTP’s scope and purpose.

D. UDP (User Datagram Protocol) is a connectionless protocol that sends data without establishing a session or ensuring delivery. This lack of reliability might seem like a disadvantage, but it's a trade-off that suits TFTP well. Because TFTP is designed for simplicity, the use of UDP on port 69 allows it to transfer files without the overhead associated with TCP. Reliability mechanisms like retransmissions and acknowledgments are handled by the application itself rather than the transport layer.

In summary, UDP is the ideal fit for TFTP due to its minimal overhead and speed, which align perfectly with the protocol’s goal of being a simple solution for file transfers in network bootstrapping or device configuration.

Question 2:

Which of the following is a correctly formatted IPv6 address?

A. 2001:0DB8::/128
B. 2001:0DB8:0:::
C. 2001:0DB8::1:1:1:1:1
D. 2001:0DB8:130F:0000:0000:7000:0000:140B

Correct Answer: D

Explanation:

IPv6 was introduced to address the limitations of IPv4, offering a vastly larger address space and improved network efficiency. An IPv6 address is 128 bits long and is typically represented as eight groups of four hexadecimal digits, each group separated by colons. The format allows certain shorthand notations, such as compressing consecutive zeros or omitting leading zeros, but strict rules govern its syntax.

Let’s evaluate the options:

A. 2001:0DB8::/128 includes a prefix length notation using CIDR, which indicates a subnet mask. While this format is valid when describing an address block or range (like a single-address subnet), it's not standard when simply displaying a single IPv6 address. The "/128" represents the entire 128-bit address space and is more about network configuration than basic address notation.

B. 2001:0DB8:0::: is not valid because it incorrectly uses the "::" compression. IPv6 allows this compression only once in an address and only for consecutive zero blocks. The use of triple colons or combining them with extra zero fields creates ambiguity and violates the syntax rules.

C. 2001:0DB8::1:1:1:1:1 attempts to use compression for zeros, but the "::" implies two zero blocks. When expanded, this address has only seven blocks instead of the required eight. IPv6 addresses must always represent exactly eight 16-bit blocks, even after expansion.

D. 2001:0DB8:130F:0000:0000:7000:0000:140B is fully expanded and follows all formatting rules. It includes exactly eight 16-bit blocks, uses valid hexadecimal values, and avoids unnecessary compression or incorrect shorthand. Although leading zeros can be removed, their inclusion does not make the address invalid—it remains syntactically correct.

In conclusion, option D correctly represents a valid IPv6 address in its full, expanded form. It adheres to all IPv6 addressing conventions, making it the correct choice.

Question 3:

Which two statements correctly describe the functionalities of Telnet and SSH? (Select two options.)

A. SSH is a protocol that enables secure remote access to network devices.
B. SSH operates on TCP port 23 for communication.
C. Telnet sessions terminate when a router is rebooted.
D. Telnet ensures secure remote access to network devices.
E. Telnet is more secure than SSH and therefore preferred.

Correct Answers: A and C

Explanation:

Understanding the differences between Telnet and SSH is essential when working with remote network device access. Let’s break down the relevant facts.

SSH (Secure Shell) is a widely used protocol that offers secure remote access to systems, such as routers, switches, and servers. What makes SSH secure is its encryption mechanism—it encrypts the entire session, including login credentials and transmitted data, which protects against packet sniffing and man-in-the-middle attacks. SSH operates on TCP port 22, not port 23 as Telnet does.

Option A is correct because SSH is explicitly designed for secure remote communication, which is crucial in environments that handle sensitive data.

Option C is also correct. Telnet, unlike SSH, does not support session persistence. When a router or similar device is rebooted, any active Telnet sessions are immediately disconnected. This behavior is expected because Telnet lacks mechanisms to maintain connections through device restarts.

Option B is incorrect because it wrongly states that SSH uses TCP port 23. Port 23 is designated for Telnet, while SSH uses port 22.

Option D is also incorrect. Telnet does not provide secure communication; it transmits data, including usernames and passwords, in plaintext. This lack of encryption makes Telnet highly vulnerable to interception and unauthorized access.

Option E is false as well. SSH is universally preferred over Telnet for security reasons. It ensures data confidentiality and integrity during remote access, while Telnet does not.

In summary, SSH offers encrypted remote connections, ensuring secure communication, and Telnet sessions do not survive device reboots. Hence, A and C are the correct statements.

Question 4:

Which type of address is primarily responsible for guiding packets across different networks in an IP-based system?

A. Physical
B. Transport
C. Network
D. MAC

Correct Answer: C

Explanation:

Routing packets across different networks relies on network-level addressing, most commonly IP addresses. These addresses play a vital role in the Network Layer (Layer 3) of the OSI model, where routing decisions are made.

Option C is correct because the network address, such as an IP address, is used to uniquely identify a device on a network and helps routers determine the most efficient path for forwarding data to its destination. IP addresses contain network and host identifiers, enabling routing across complex topologies that include multiple networks and subnets.

Routers, which function at Layer 3, examine destination IP addresses in each packet to decide how to forward it through the network. This allows for end-to-end communication, even when the devices are not on the same local network.

Option A, the physical address, refers to a MAC address, which is assigned to a network interface card (NIC). It operates at the Data Link Layer (Layer 2) and is used primarily for local delivery within the same broadcast domain. MAC addresses are not visible to routers when forwarding traffic between different networks, and thus do not facilitate inter-network routing.

Option B, the transport address, refers to port numbers (like TCP or UDP ports). These are used at Layer 4 to deliver data to the correct application on the destination device. While essential for application-level communication, transport addresses do not influence the routing of packets across networks.

Option D, MAC address, is effectively a repeat of Option A and is similarly incorrect for the same reason: MAC addresses support local network communication, but not the routing of packets across separate IP networks.

Therefore, the network address is the key element that facilitates routing in IP-based communication, making Option C the correct answer.

Question 5:

Which two of the following IPv4 addresses are valid and can be assigned to a host device? (Choose two.)

A. 255.255.255.255
B. 10.1.1.20
C. 0.0.0.0
D. 192.168.10.15
E. 292.10.3.4

Correct Answers: B, D

Explanation:

In IPv4 addressing, host devices can only be assigned valid, non-reserved IP addresses. Several ranges and specific addresses are set aside for special functions and cannot be allocated to individual hosts. Let’s review each of the choices to determine which are suitable for assignment.

A (255.255.255.255) is reserved as a limited broadcast address, used to send packets to all devices on a local network. It is not assignable to a host, as it serves a universal communication purpose for local subnets.

B (10.1.1.20) is a valid private IP address, falling within the reserved 10.0.0.0 to 10.255.255.255 range, designated for internal network use. It is perfectly valid for host assignment in private LAN environments.

C (0.0.0.0) is used to refer to an unknown or unspecified address and is often seen during system startup or routing configurations to represent “any” address. It cannot be assigned to a host because it has no specific network identity.

D (192.168.10.15) also belongs to the private address range (192.168.0.0 to 192.168.255.255), widely used in home and business networks. Like 10.1.1.20, it is assignable to hosts within a private network.

E (292.10.3.4) is not valid because IPv4 octets must range between 0 and 255. The first octet here exceeds that maximum, making it an invalid IP address.

To summarize, valid and assignable addresses must fall within allowed ranges and not be reserved for special functions. Only B and D meet these criteria. These private addresses can be used within LANs, enabling communication between hosts and routers, and are widely used in internal networking scenarios.

Question 6:

Which two components are essential for establishing a Wide Area Network (WAN) connection? (Choose two.)

A. CSU/DSU
B. Router
C. Bridge
D. Hub
E. Switch

Correct Answers: A, B

Explanation:

A Wide Area Network (WAN) connects devices across large geographical areas, often linking separate local area networks (LANs) through public or private data carriers. Certain hardware components are essential for enabling these wide-reaching connections.

A (CSU/DSU), short for Channel Service Unit/Data Service Unit, acts as an interface between a router and a digital transmission circuit, such as a leased telephone line. It converts the digital signal used within the internal network into a format acceptable for transmission over WAN service provider lines. The CSU/DSU handles synchronization and signal formatting, making it a critical component for older WAN technologies like T1 or E1 lines.

B (Router) is another fundamental device in WAN setups. A router forwards data between different networks and determines the best path for data transmission. In WAN configurations, routers connect the internal LAN to the external network, ensuring that packets are correctly routed across potentially vast distances to their final destinations.

Now, let’s examine why the remaining options are not suitable components for WAN:

C (Bridge) is primarily used to connect segments within the same LAN. Operating at Layer 2 of the OSI model, it does not have the capability to route traffic across multiple networks like a router does, making it unsuitable for WAN usage.

D (Hub) functions at Layer 1 and simply repeats signals to all connected devices. It cannot distinguish between devices or handle data routing and is thus restricted to small LANs. Hubs are outdated and not applicable in WAN scenarios.

E (Switch) works at Layer 2 and helps manage traffic within a LAN by forwarding data based on MAC addresses. While vital in internal network performance, switches don’t have routing capabilities required for WAN communication.

In conclusion, the CSU/DSU provides the necessary interface to the service provider’s network, and the router handles path selection and data forwarding. Together, they form the backbone of any WAN connection, making A and B the correct answers.

Question 7:

Which of the following devices functions as a Data Terminal Equipment (DTE)?

A. CSU/DSU
B. Router
C. Cable modem
D. DSL modem

Correct Answer: B

Explanation:

A Data Terminal Equipment (DTE) device is typically defined as an endpoint in a data communication system that either originates or receives digital data. It plays a critical role in initiating, processing, or terminating communication sessions. Among the options provided, the router is the best example of a DTE device.

Routers are responsible for directing traffic within or between networks. They operate at the network layer of the OSI model and determine the best path for forwarding packets. In many networking environments, routers connect to external networks via intermediary devices such as modems or CSU/DSUs, but the router itself serves as the terminal equipment handling and processing the actual data—this qualifies it as a DTE.

Now, let’s examine the other options:

A. CSU/DSU (Channel Service Unit/Data Service Unit) is not a DTE device. It is considered Data Circuit-Terminating Equipment (DCE). Its role is to convert digital signals from the DTE (like a router) into a format suitable for transmission over a service provider’s digital lines (e.g., T1). The CSU/DSU manages the line coding and synchronization but does not initiate or terminate communication in the way DTEs do.

C. Cable modems and D. DSL modems are both forms of DCE devices. While they do connect networks and allow data to be transmitted over broadband connections, they do not initiate or process data the way routers do. These devices typically serve as bridges between a DTE (like a router or computer) and the physical medium provided by the ISP.

To summarize, DTE devices are generally responsible for data creation, manipulation, and termination, while DCE devices facilitate the actual transmission over the network. Because a router fits the description of a DTE—it handles data processing and initiates communication—it is the correct choice. Therefore, B is the right answer.

Question 8:

Which OSI layer determines the format of transmitted data and controls access to the physical network medium?

A. Presentation
B. Data Link
C. Network
D. Transport

Correct Answer: B

Explanation:

Within the OSI (Open Systems Interconnection) model, the Data Link layer—which is the second layer—is responsible for ensuring that data is correctly formatted for transmission and managing how devices access the physical medium (like cables or wireless signals).

The Data Link layer plays several important roles. It takes raw bits from the Physical layer and organizes them into frames, which are structured packets of data. These frames include not only the actual payload but also headers and trailers that contain control information, such as error checking mechanisms like CRC (Cyclic Redundancy Check).

Additionally, the Data Link layer determines when a device can transmit data by managing media access control. In networks like Ethernet, this involves using protocols such as CSMA/CD (Carrier Sense Multiple Access with Collision Detection) to avoid data collisions. The layer also handles addressing at the MAC (Media Access Control) level, assigning and recognizing hardware addresses (MAC addresses).

Now let’s consider why the other options are incorrect:

A. Presentation layer deals with how data is represented, encoded, or encrypted for the application layer. It has nothing to do with the transmission formatting or media access.

C. Network layer is responsible for logical addressing (like IP addresses) and routing data across different networks. It doesn’t handle access to the physical medium or define the format for transmitting over a specific link.

D. Transport layer manages the end-to-end delivery of data, including reliability, flow control, and error correction, but not media access or physical formatting.

In conclusion, the Data Link layer is essential for framing the data for transmission and controlling access to the physical medium, which is why B is the most accurate answer.

Question 9:

Which command should be used to display the current condition of power supplies and temperature sensors on a network device?

A. show hardware
B. show module
C. show environment
D. show diag

Correct Answer: C

Explanation:

To monitor the environmental health of a network device, including its power supplies, fan units, and temperature sensors, the most appropriate command is show environment. This command offers a detailed report of environmental conditions, which is essential for maintaining proper device functionality and avoiding hardware failure due to overheating or power issues.

The show environment command typically includes information such as:

• The operational status of all power supply units (PSUs)

• The current temperature readings from internal sensors

• The condition and performance of cooling fans

• Voltage levels and threshold alerts for potential hardware malfunctions

Monitoring this data is crucial in data centers and enterprise environments, where overheating or failed components can lead to service disruptions or damage.

Now let’s evaluate the other options:

A. The show hardware command provides a list of installed hardware components, such as CPU, memory, or interfaces. However, it does not offer information on power or temperature metrics, which are vital for environmental monitoring.

B. show module displays the operational status of installed modules, like line cards or supervisor engines. While this may reveal whether modules are online or functional, it does not cover environmental details such as temperature or power supply status.

D. show diag generates diagnostic data related to hardware performance and may report failures or errors in modules. Although it can be useful for troubleshooting, it doesn’t serve as the primary tool for monitoring real-time environmental conditions.

In conclusion, the show environment command is specifically designed for assessing the health of hardware in terms of environmental conditions. It is the most reliable way to check temperature readings, power supply status, and fan performance, making C the correct answer.

Question 10:

Which of the following are recognized as standard types of fiber-optic connectors? (Select two.)

A. Lucent
B. rollover
C. subscriber
D. multidimension
E. crossover

Correct Answers: A & C

Explanation:

Fiber-optic connectors are specialized components used to terminate and connect fiber-optic cables to networking equipment, enabling high-speed data transmission with minimal loss. Two widely accepted and standard fiber-optic connectors are Lucent (LC) and Subscriber (SC) connectors.

Lucent Connector (LC):
Often abbreviated as LC, this small form-factor connector is valued for its compact size and high performance. It uses a 1.25 mm ferrule, which makes it ideal for high-density environments like data centers. LC connectors feature a latch mechanism, offering a secure connection and ease of use.

Subscriber Connector (SC):
SC connectors, also known as Subscriber Connectors, are another common type. They use a 2.5 mm ferrule and are well known for their durability and simple push-pull locking mechanism. SC connectors are frequently used in both single-mode and multimode fiber-optic networks due to their reliability and ease of installation.

Now, let’s examine the incorrect options:

B. Rollover cables are used for console access in networking and are not fiber-optic connectors. These are standard copper cables used to connect a computer to a router or switch’s console port.

D. Multidimension is not a recognized term in the fiber-optic industry. It does not refer to any type of connector or cable used in standard network infrastructure.

E. Crossover cables are Ethernet cables configured to connect similar networking devices directly (like switch-to-switch). These are twisted-pair copper cables, not fiber-optic connectors.

In summary, Lucent (LC) and Subscriber (SC) are industry-standard fiber-optic connectors widely used in modern network installations. Hence, the correct answers are A and C.