Cisco 200-301 Cisco Certified Network Associate (CCNA) Exam Dumps and Practice Test Questions Set 6 Q76-90
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Question 76
Which protocol is used for network device management and monitoring?
A) SNMP
B) HTTP
C) FTP
D) SMTP
Answer: A) SNMP
Explanation
Simple Network Management Protocol, commonly referred to as SNMP, is a fundamental tool for network administrators who need to monitor, configure, and manage devices across a network. SNMP is designed specifically to facilitate the management of networked devices such as switches, routers, servers, and printers. Its primary function is to allow administrators to remotely collect data on device performance, track network statistics, and receive alerts when predefined thresholds are exceeded. By doing so, SNMP helps maintain network health, ensures efficient operation, and allows rapid identification of potential issues before they escalate into significant problems.
SNMP operates by using agents installed on network devices, which communicate with a centralized management system, often called a Network Management System (NMS). These agents collect various metrics, including bandwidth usage, CPU utilization, memory consumption, interface status, and error rates, among others. The management system can query devices for this information at regular intervals, providing a comprehensive view of the network’s performance. Additionally, SNMP supports traps, which are asynchronous notifications sent from devices to the management system to signal critical events or threshold violations. This combination of polling and traps ensures administrators can monitor both normal operation and exceptional conditions effectively, allowing proactive network management.
Other protocols, while useful for different tasks, are not dedicated to network monitoring and management in the same way SNMP is. HTTP, for instance, can be used to access web-based management interfaces on network devices. Through a web browser, administrators can configure settings, view logs, or check status. However, HTTP does not provide a standardized mechanism for continuously monitoring network performance or automatically sending alerts. It is primarily a manual interface for configuration and status checking, rather than a comprehensive monitoring solution.
FTP, or File Transfer Protocol, serves a completely different purpose. Its main function is to transfer files between systems over a network. While it is essential for moving data and supporting software updates or backups, FTP does not have built-in capabilities to monitor network health, collect performance metrics, or alert administrators about device issues. Its role in network management is indirect at best, as it might be used to move configuration files but cannot actively track device performance or network conditions.
SMTP, or Simple Mail Transfer Protocol, is primarily concerned with email delivery. It is designed to send and receive messages between mail servers and clients. While email notifications can sometimes be triggered by monitoring systems, SMTP itself is not a monitoring tool. It does not collect device statistics, track performance, or enable remote configuration. It functions solely as a communication protocol for email, making it unrelated to the direct monitoring and management of network infrastructure.
Given these differences, SNMP is uniquely suited for the continuous monitoring, configuration, and management of network devices. Its standardized approach, ability to collect detailed statistics, and support for automated alerts make it the most effective choice for administrators who need to maintain operational efficiency and quickly respond to network issues. Therefore, when the requirement is to monitor and manage network devices, SNMP is the correct solution.
Question 77
Which command saves the running configuration to NVRAM on a Cisco device?
A) copy running-config startup-config
B) show running-config
C) write erase
D) reload
Answer: A) copy running-config startup-config
Explanation
Straight-through cables are a type of Ethernet cable commonly used in networking to connect devices that operate on different layers or functions within a network. One of the primary uses of straight-through cables is to connect end devices, such as personal computers, laptops, or workstations, to networking hardware like switches, hubs, or routers. These cables are designed so that the transmit and receive pairs on one end of the cable match the corresponding pairs on the other end, ensuring proper communication between the devices. By maintaining this alignment, data can flow correctly from the transmitting device to the receiving device without errors or signal collisions. This makes straight-through cables essential for typical client-to-network connections in both small and large networks.
The distinction between straight-through and other types of cables lies in how the individual wires within the cable are terminated. In a straight-through cable, the pinouts on both ends of the cable follow the same wiring standard, either T568A or T568B. This consistency ensures that the transmitting pins on one device connect to the receiving pins on the other, which is necessary when connecting devices with different functions, such as a PC and a switch. Using a straight-through cable in this scenario allows the devices to communicate immediately and reliably, supporting the exchange of data packets, internet traffic, and other network services.
Crossover cables, by contrast, are intended for connecting similar devices directly, such as switch-to-switch, router-to-router, or PC-to-PC connections in specific situations. In crossover cables, the transmit and receive pairs are intentionally reversed on one end of the cable, which allows the devices to communicate without an intermediary switch or hub. While crossover cables were more commonly required in older network setups, modern switches often support auto-MDI/MDIX functionality, which can automatically detect and adjust for the type of cable connected. Nevertheless, understanding the distinction remains important, particularly in environments with legacy equipment.
Rollover cables serve yet another purpose. They are typically used to establish console connections between a PC or terminal and the console port of a network device, such as a switch or router, for configuration purposes. These cables have a different pinout configuration that essentially “rolls over” the wiring from one end to the other, which is why they are named rollover cables. They are not suitable for regular network traffic between devices because they do not align the transmit and receive pairs in a way that supports Ethernet communication.
Fiber patch cables provide optical connectivity and are used to connect devices with fiber interfaces, such as switches with SFP modules or routers with fiber ports. While fiber cables can support longer distances and higher speeds than copper Ethernet cables, they require compatible interfaces and transceivers, making them unsuitable for a standard PC-to-switch connection unless both devices have fiber ports and modules installed.
Because the question specifically asks about connecting a PC to a switch, the correct choice is a straight-through cable. This type of cable ensures proper alignment of transmit and receive pairs between dissimilar devices, allowing reliable data transmission and seamless network connectivity. Straight-through cables remain the standard solution for connecting end devices to network infrastructure in nearly all Ethernet-based networks.
Question 78
Which command verifies connectivity to a remote host?
A) ping
B) traceroute
C) show ip route
D) show interfaces
Answer: A) ping
Explanation
The command copy running-config startup-config is an essential function in network device management because it saves the active configuration stored in RAM to non-volatile memory, or NVRAM. When a network administrator makes changes to a device’s configuration, such as modifying interface settings, adjusting routing protocols, or updating VLAN assignments, these changes are immediately applied to the running configuration in RAM. This running configuration represents the current operational state of the device, reflecting all recent modifications. However, because RAM is volatile memory, any unsaved changes are lost if the device loses power or is restarted. To prevent configuration loss and ensure that all adjustments persist across reboots, the copy running-config startup-config command must be executed. This action copies the live configuration to NVRAM, which is retained even when the device is powered off, ensuring continuity in network operations.
By contrast, show running-config serves a different purpose. This command displays the device’s current configuration as it exists in RAM, providing administrators with a real-time view of active settings. It is an invaluable tool for verifying configurations, troubleshooting issues, and confirming that recent changes have been correctly applied. However, show running-config does not save the configuration to NVRAM. If a device restarts without first executing the copy command, all modifications present in the running configuration will be lost, and the device will revert to the last saved startup configuration. This distinction is critical for network reliability because understanding the difference between viewing and saving configurations ensures that changes are properly preserved.
Write erase, also known as erase startup-config, is another command often associated with configuration management. Its purpose is to delete the existing startup configuration stored in NVRAM, essentially resetting the device to a default state. While this command is useful for clearing configurations or preparing a device for redeployment, it does not save any changes from the running configuration. Using write erase without first copying the running configuration to startup-config would result in the permanent loss of any unsaved settings, highlighting the importance of the copy command for preservation.
Reload is another important but distinct command in network device management. When a reload is executed, the device restarts and loads the configuration from NVRAM, effectively replacing the running configuration in RAM with the saved startup configuration. If any recent changes in the running configuration were not saved using copy running-config startup-config, those changes are lost during the reload process. This behavior underscores the critical role of the copy command in ensuring that administrative modifications are not inadvertently discarded during routine maintenance, power cycles, or device reboots.
Because the question specifically asks about saving the running configuration so that it persists across device reboots, the correct command is copy running-config startup-config. This command ensures that all recent configuration changes are preserved, maintaining network stability and operational continuity. Without executing this command, changes applied to the running configuration remain temporary and vulnerable to loss, making copy running-config startup-config a fundamental practice for reliable network administration.
Question 79
Which command displays the IOS version and device uptime?
A) show version
B) show running-config
C) show ip interface brief
D) show startup-config
Answer: A) show version
Explanation
The command show version is an important tool for network administrators because it provides comprehensive information about the device, allowing administrators to quickly assess both software and hardware details. When executed, show version displays critical data including the IOS version running on the device, the system uptime, the device’s hardware model, memory capacity, and configuration register settings. This information is vital for troubleshooting, planning upgrades, performing maintenance, and understanding the overall state of the device. Knowing the IOS version helps determine feature availability, compatibility with other devices, and whether patches or updates are necessary. System uptime provides insight into device stability, recent reboots, or potential issues related to power cycles or unexpected crashes. Hardware and memory information ensures administrators are aware of the device’s capacity and limitations, which can impact network performance and scalability. The configuration register setting is also displayed, which can influence how the device boots and loads its configuration.
In contrast, show running-config serves a different purpose. This command provides a snapshot of the current, active configuration stored in RAM. It lists interface configurations, routing protocols, VLAN assignments, access control lists, and other applied settings. While this information is essential for monitoring the live configuration and verifying that changes have been applied correctly, it does not include system-level details such as the IOS version, memory, or uptime. Therefore, show running-config is not suitable when the objective is to obtain system information about the device itself, rather than its configuration.
Another frequently used command is show ip interface brief. This command is designed to provide a concise status of network interfaces and their IP address assignments. Administrators can quickly determine which interfaces are operational, administratively shut down, or misconfigured. While show ip interface brief is useful for troubleshooting connectivity issues and verifying IP addressing, it does not provide system-level information such as the IOS version, hardware, memory, or uptime. Its focus is limited to interface operational status and IP assignments.
Show startup-config is used to display the configuration stored in NVRAM, which is loaded when the device boots. This command allows administrators to see the saved configuration that will be applied after a reboot, making it useful for verifying that changes have been correctly saved. However, like show running-config, it does not provide information about the IOS version, system uptime, hardware details, or memory. It is limited to displaying configuration data and cannot fulfill the requirement of identifying the device’s software version or operational history.
Given the distinctions between these commands, show version is uniquely suited for the task of displaying IOS version and system uptime. It provides a complete view of both hardware and software information, which is critical for effective device management, maintenance planning, and troubleshooting. Because the question specifically asks for details about the IOS version and the system uptime, show version is the correct command. It offers comprehensive system-level insights that none of the other commands provide, making it an indispensable tool for administrators seeking to understand the device’s operational state and software environment.
Question 80
Which command displays interface statistics including errors and collisions?
A) show interfaces
B) show ip route
C) show mac address-table
D) show arp
Answer: A) show interfaces
Explanation
The show interfaces command is a critical tool used by network administrators to monitor and troubleshoot the performance and status of network interfaces on devices such as routers and switches. This command provides a comprehensive view of each interface, including its operational status, assigned IP addresses, input and output statistics, error counts, collisions, packet drops, and other important metrics. These details are essential for diagnosing network issues because they allow administrators to identify whether an interface is functioning correctly and whether any physical or data-link layer problems are affecting network performance. By using show interfaces, administrators can quickly detect issues such as misconfigurations, hardware failures, congestion, or other anomalies that might be impacting the flow of traffic through the network.
One of the most valuable aspects of show interfaces is its ability to report interface errors. These errors can include CRC errors, input errors, output errors, collisions, and frame errors. CRC errors indicate data corruption during transmission, often caused by faulty cabling, electromagnetic interference, or malfunctioning hardware. Input and output errors reflect problems in receiving or sending frames, which could be the result of buffer overflows, hardware issues, or misconfigurations. Collisions, while less common in full-duplex networks, occur when two devices attempt to transmit data simultaneously on a shared medium, leading to retransmissions and reduced network efficiency. By analyzing these statistics, administrators can pinpoint the root causes of performance issues and take corrective actions, such as replacing cables, adjusting interface settings, or reconfiguring the network topology.
In contrast, the show ip route command provides information about the device’s routing table, including directly connected networks, static routes, and routes learned through dynamic routing protocols. While this command is essential for understanding how a device forwards packets at the network layer and for troubleshooting routing issues, it does not provide any information about interface errors, collisions, or packet drops. Therefore, show ip route cannot be used to diagnose physical or data-link layer problems.
The show mac address-table command displays the MAC addresses learned by a switch and the ports associated with those addresses. This information is valuable for identifying which devices are connected to specific ports, verifying VLAN configurations, and troubleshooting Layer 2 connectivity issues. However, show mac address-table does not report operational status, error counts, or collisions for interfaces, so it does not provide the detailed diagnostic information needed to assess interface health.
Similarly, the show arp command lists IP-to-MAC address mappings maintained by a device. This helps administrators verify address resolution and troubleshoot local communication issues, but it does not provide statistics about interface performance, error counts, or collisions. ARP information is important for Layer 3 troubleshooting within a subnet but does not address physical or data-link layer problems on interfaces.
Because the question specifically asks for monitoring errors and collisions on network interfaces, show interfaces is the correct choice. It uniquely provides detailed, real-time information about the operational status and performance of interfaces, enabling administrators to identify and resolve network problems at both the physical and data-link layers. No other command listed provides this level of detail for troubleshooting interface-related issues, making show interfaces the most appropriate tool for the task.
Question 81
Which protocol resolves IP addresses to MAC addresses on a local network?
A) ARP
B) DNS
C) DHCP
D) ICMP
Answer: A) ARP
Explanation
Address Resolution Protocol, commonly known as ARP, is a fundamental network protocol used to map IP addresses to their corresponding MAC addresses within a local network. This process is essential for the proper delivery of data packets across Ethernet or other Layer 2 networks. While IP addresses operate at Layer 3 and are used for logical addressing and routing across networks, MAC addresses operate at Layer 2 and identify the physical hardware interfaces of devices on the same local segment. ARP serves as the bridge between these two layers, ensuring that data intended for a specific IP address reaches the correct device by identifying its MAC address. Without ARP, devices would not know how to forward packets on the local network, and communication within the subnet would fail.
When a device needs to communicate with another host on the same local network, it first checks its ARP cache to see if the mapping for the target IP address is already known. If the MAC address is not present in the cache, the device broadcasts an ARP request to all devices on the local subnet, asking which device owns the specific IP address. The device that owns the requested IP responds with its MAC address. The requesting device then stores this information in its ARP cache for future communications, reducing the need for repeated broadcasts. This mechanism ensures that communication within the subnet is efficient and accurate, allowing devices to send frames to the correct destination.
In comparison, the Domain Name System, or DNS, serves a very different function. DNS translates human-readable hostnames into IP addresses, enabling users to access websites, servers, and network resources without memorizing numerical addresses. While DNS is crucial for locating resources by name and facilitating network communication, it does not provide MAC address information and therefore cannot be used to deliver frames at the local network level. DNS operates at a higher layer, focusing on logical address resolution rather than physical delivery.
Dynamic Host Configuration Protocol, or DHCP, is responsible for assigning IP addresses and other network configuration parameters, such as subnet masks, default gateways, and DNS server addresses, to devices automatically. While DHCP simplifies network management by ensuring devices have valid IP addresses, it does not resolve IP addresses to MAC addresses. Its function is primarily related to configuration rather than the operational task of mapping addresses for packet delivery on a local network.
Internet Control Message Protocol, or ICMP, is used for network diagnostics and error reporting. Tools such as ping and traceroute rely on ICMP to test connectivity, measure round-trip time, and report unreachable destinations. While ICMP is essential for troubleshooting network performance and connectivity issues, it does not perform IP-to-MAC mapping and therefore cannot facilitate the delivery of packets on a local network.
Since the question specifically asks about resolving IP addresses to MAC addresses, ARP is the correct protocol. It uniquely provides the mechanism for mapping logical addresses to physical hardware addresses, enabling accurate and efficient delivery of packets within a subnet. None of the other protocols mentioned—DNS, DHCP, or ICMP—perform this critical function, making ARP indispensable for local network communication.
Question 82
Which routing protocol uses distance vector metrics?
A) RIP
B) OSPF
C) EIGRP
D) BGP
Answer: A) RIP
Explanation
Routing Information Protocol, commonly referred to as RIP, is one of the earliest and most widely known distance-vector routing protocols used in networking. Its primary function is to enable routers to dynamically share routing information with neighboring devices, allowing them to learn about network paths and determine the best routes for delivering packets. RIP operates using a simple distance-vector algorithm, where the distance to a network is measured in terms of hop count. Each router periodically sends its entire routing table to its directly connected neighbors, and routers use this information to update their own tables. The maximum number of hops allowed in RIP is 15, which limits the size of networks in which RIP can operate effectively. Any network beyond 15 hops is considered unreachable, which helps prevent routing loops in larger environments.
The key characteristic of RIP is its use of hop count as the sole metric for determining the best path. This simplicity makes RIP easy to configure and understand, but it also limits its scalability and adaptability. Because it only considers the number of hops, RIP does not take into account other factors such as bandwidth, delay, or network congestion. This can lead to situations where the chosen path is not the most efficient in terms of actual performance, even though it has the fewest hops. Despite these limitations, RIP remains a foundational protocol for learning about distance-vector routing principles and is still used in some small or legacy networks due to its straightforward operation.
In contrast, OSPF, or Open Shortest Path First, is a link-state routing protocol. OSPF uses a different approach by maintaining a complete map of the network topology and calculating the shortest path to each destination using Dijkstra’s algorithm. The metric OSPF uses, known as cost, is based primarily on link bandwidth, allowing it to select routes that optimize performance rather than simply counting hops. OSPF routers exchange link-state advertisements (LSAs) rather than entire routing tables, enabling faster convergence and more efficient use of network resources. Because OSPF uses a link-state method rather than distance-vector, it does not rely on hop count as its metric, making it a fundamentally different type of routing protocol.
EIGRP, or Enhanced Interior Gateway Routing Protocol, is considered a hybrid or advanced distance-vector protocol. While it does share some characteristics with traditional distance-vector protocols like RIP, EIGRP uses multiple metrics—including bandwidth, delay, load, and reliability—to calculate the best path. This allows EIGRP to make more informed routing decisions and support larger, more complex networks. Its metric calculations are more sophisticated than RIP’s simple hop count, and it supports faster convergence and loop prevention mechanisms through techniques such as the Diffusing Update Algorithm.
BGP, or Border Gateway Protocol, is an exterior gateway protocol that operates primarily on the internet to manage routing between autonomous systems. BGP uses a path vector approach, considering policies, path attributes, and AS numbers to determine the best route. It does not rely on hop count or distance-vector methods.
Because the question specifies a protocol that uses distance-vector metrics based on hop count, RIP is the correct choice. It is the classic example of a distance-vector protocol, using periodic updates and simple hop count calculations to determine network reachability, distinguishing it from link-state, hybrid, or path vector protocols.
Question 83
Which protocol provides reliable, connection-oriented communication between devices?
A) TCP
B) UDP
C) ICMP
D) ARP
Answer: A) TCP
Explanation
Transmission Control Protocol, commonly referred to as TCP, is one of the core protocols of the Internet Protocol suite and plays a fundamental role in ensuring reliable, connection-oriented communication between devices on a network. TCP is designed to provide a structured and dependable method for transmitting data over IP networks, addressing the limitations of the underlying Internet Protocol, which is inherently connectionless and does not guarantee delivery. One of the primary features of TCP is its ability to establish a connection between a sender and a receiver before transmitting data. This process, known as the three-way handshake, ensures that both ends are ready to communicate and can reliably exchange data. Once the connection is established, TCP manages the transmission of data in a way that guarantees all packets arrive at the destination in the correct order.
TCP achieves reliability through several mechanisms. First, it uses sequence numbers to label each byte of data, allowing the receiving device to reconstruct the original message even if packets arrive out of order. Second, TCP implements acknowledgment messages, where the receiver confirms successful receipt of data segments. If the sender does not receive an acknowledgment within a specified timeout period, it retransmits the unacknowledged data, ensuring that no information is lost. Third, TCP employs flow control to prevent a fast sender from overwhelming a slower receiver, maintaining smooth and efficient data transfer. Additionally, TCP uses congestion control techniques to adjust the rate of transmission based on network conditions, helping to prevent congestion collapse and maintain overall network performance. These combined features make TCP a reliable protocol for applications that require guaranteed delivery, such as web browsing, email, file transfers, and database synchronization.
In contrast, User Datagram Protocol, or UDP, is a connectionless transport protocol. Unlike TCP, UDP does not establish a session between the sender and receiver, and it does not provide sequencing, acknowledgment, or retransmission of lost packets. UDP is lightweight and efficient, making it suitable for applications that prioritize speed over reliability, such as video streaming, online gaming, or voice over IP. While UDP can deliver data quickly, it cannot ensure that all packets arrive or that they arrive in order, and therefore it does not meet the requirements of scenarios that demand guaranteed, connection-oriented communication.
Internet Control Message Protocol, or ICMP, is used primarily for network diagnostics and error reporting. Tools like ping and traceroute rely on ICMP to test connectivity, measure latency, and identify unreachable hosts. While ICMP is valuable for troubleshooting and network monitoring, it does not provide transport-layer reliability or sequencing of data and therefore cannot be used for reliable data delivery.
Address Resolution Protocol, or ARP, operates at the data-link layer and maps IP addresses to MAC addresses within a local network. While ARP is essential for enabling devices to communicate on the same subnet, it does not provide transport-layer functionality, reliability, or ordered delivery of packets.
Because the question specifically focuses on reliable, connection-oriented communication, TCP is the correct protocol. It uniquely combines connection establishment, sequencing, acknowledgment, retransmission, and flow control to ensure data is delivered accurately and in order, making it indispensable for reliable network communication. None of the other protocols listed provide the same level of reliability or connection-oriented features as TCP, which is why it is the appropriate choice in this context.
Question 84
Which type of IPv4 address is used to communicate with all devices in a network segment?
A) Broadcast
B) Unicast
C) Multicast
D) Anycast
Answer: A) Broadcast
Explanation
Broadcast addresses are a fundamental aspect of networking that allow a single packet to be delivered to all devices within a specific subnet. When a device sends a packet to a broadcast address, every host on the subnet receives the packet, enabling one-to-all communication. This capability is essential for several network operations where information must be shared simultaneously with all devices on a local network segment. One of the most common uses of broadcast addresses is in Address Resolution Protocol (ARP) requests. When a device needs to determine the MAC address corresponding to a particular IP address, it sends an ARP request to the broadcast address of the subnet. Every device receives the request, but only the device with the matching IP responds with its MAC address, allowing the requesting device to update its ARP table and continue communication. Broadcast communication ensures that devices can discover each other dynamically without prior knowledge of individual MAC addresses, which is critical for the functionality of IP networks.
Broadcast addresses are also used for other types of network-wide communication, such as certain types of service announcements, dynamic host configuration tasks, and management messages. For example, some protocols use broadcast to announce services or resources to all devices in a subnet, facilitating automatic configuration or discovery without requiring manual intervention. By sending a message to all devices at once, broadcast reduces the complexity of communication and ensures that every host in the subnet receives the information. This one-to-all capability distinguishes broadcast communication from other addressing methods, where packets are sent to either a single host or a subset of devices.
In comparison, unicast communication is designed for one-to-one delivery. When a device sends a packet to a unicast address, the packet is delivered only to the intended recipient. Unicast is efficient for point-to-point communication, such as sending data to a specific server or client, because it avoids unnecessary transmission to devices that do not require the data. However, unicast is not suitable for scenarios where all devices on a subnet need to receive the same information, as it would require sending individual packets to each host, increasing network overhead.
Multicast addresses provide one-to-many communication, allowing packets to be delivered to multiple devices that have joined a specific multicast group. Multicast is useful for streaming media, group messaging, or sending updates to selected devices, but it does not reach every device on the subnet unless all devices have explicitly subscribed to the multicast group.
Anycast addresses are used to deliver packets to the nearest or best-performing device among a group of hosts sharing the same address. Anycast is commonly used for load balancing or routing optimization, directing traffic to the closest server, but it does not provide communication to all devices in a subnet.
Because the question specifies communication with all devices in a subnet, broadcast is the correct addressing method. It ensures that a single transmission reaches every host, supporting ARP requests and other network-wide operations, which none of the other addressing methods can achieve. Broadcast uniquely provides one-to-all delivery, making it essential for efficient subnet-wide communication.
Question 85
Which VLAN type carries voice traffic separately for prioritization?
A) Voice VLAN
B) Management VLAN
C) Native VLAN
D) Data VLAN
Answer: A) Voice VLAN
Explanation
Voice VLANs are a specialized type of VLAN configuration designed to separate voice traffic from regular data traffic on a network. In modern enterprise networks, many organizations use Voice over IP (VoIP) technology to handle telephone communications over the same network infrastructure used for data. Because voice traffic is highly sensitive to delay, jitter, and packet loss, it requires a higher level of priority compared to standard data traffic. By creating a dedicated voice VLAN, network administrators can isolate voice packets and apply Quality of Service (QoS) policies to ensure that voice communications maintain consistent clarity and reliability, even during periods of high network utilization. This separation is particularly important in environments where large amounts of data traffic could otherwise interfere with real-time voice transmission.
Typically, voice VLANs are configured on switch ports that connect to IP phones. These ports are often configured to carry both data and voice traffic from the same physical connection, but with the traffic logically separated using VLAN tagging. The IP phone tags its own voice traffic with the designated voice VLAN, while untagged data traffic from the connected computer or other device remains in the data VLAN. This configuration allows a single port to support multiple types of traffic while ensuring that voice data is prioritized and routed efficiently through the network. Switches can then use QoS mechanisms to prioritize voice packets over data packets, reducing latency and jitter and preventing call quality from degrading during periods of network congestion.
In contrast, a management VLAN serves a completely different purpose. Management VLANs are used to provide administrators with access to network devices such as switches and routers for monitoring, configuration, and maintenance. By isolating management traffic into a dedicated VLAN, network security is enhanced, and administrative access can be controlled more effectively. Management VLANs do not prioritize voice traffic or handle real-time communication and are therefore not suitable for ensuring high-quality voice transmissions.
The native VLAN, on the other hand, is used primarily on trunk ports to handle untagged traffic. It allows devices that do not support VLAN tagging to communicate across the network but does not provide traffic prioritization or separation for voice or data. While the native VLAN ensures compatibility and basic connectivity, it does not address the specific requirements of VoIP traffic or the need for low-latency, high-priority transmission.
Data VLANs carry general user data traffic, such as file transfers, email, web browsing, and application communication. While data VLANs are essential for the functioning of the network, they are not designed to prioritize traffic based on latency or quality of service. Mixing voice traffic with high-volume data traffic without separation can lead to degraded call quality and increased packet loss, which is why voice VLANs are necessary in networks that handle IP telephony.
Because the question specifies the prioritization and separation of voice traffic, the correct solution is a voice VLAN. Voice VLANs uniquely provide the capability to isolate and prioritize voice packets, apply QoS policies, and ensure consistent call quality, which none of the other VLAN types—management, native, or data—are specifically designed to do.
Question 86
Which command displays the MAC address table on a switch?
A) show mac address-table
B) show arp
C) show ip route
D) show interfaces
Answer: A) show mac address-table
Explanation
The show mac address-table command is a crucial tool used in network management to display all MAC addresses that a switch has learned and the corresponding ports on which these devices are connected. In an Ethernet network, each device has a unique Media Access Control (MAC) address that identifies it at the data link layer. Switches use these MAC addresses to forward traffic efficiently by learning which devices are connected to which ports and building a MAC address table. This table allows the switch to send frames directly to the intended destination port rather than broadcasting them to all ports, which improves network efficiency and reduces unnecessary traffic. The show mac address-table command provides administrators with a detailed view of this information, making it easier to troubleshoot connectivity issues, verify network configurations, and manage VLAN assignments.
When a device sends a frame on a switch port, the switch examines the source MAC address and records it in the MAC address table along with the port it was received on. This learning process is dynamic and updates continuously as devices join, leave, or move within the network. By running show mac address-table, administrators can confirm that the switch has correctly learned the MAC addresses of connected devices, identify which ports are actively being used, and detect any discrepancies that might indicate network problems such as misconfigurations, loops, or unauthorized devices. This command is especially useful for verifying VLAN memberships and ensuring that devices are communicating on the correct segments of the network.
In comparison, the show arp command serves a different purpose. ARP, or Address Resolution Protocol, maps IP addresses to MAC addresses within a local network. The show arp command displays these IP-to-MAC mappings, which helps administrators verify that devices can resolve addresses and communicate at the local layer. However, show arp does not provide a view of the switch’s MAC address table or indicate which ports devices are connected to. Therefore, while useful for troubleshooting address resolution issues, it does not replace the functionality of show mac address-table for port-level connectivity verification.
The show ip route command provides information about a router or Layer 3 device’s routing table, listing directly connected networks, static routes, and routes learned through dynamic routing protocols. While show ip route is essential for understanding how traffic is forwarded at the network layer and for diagnosing routing problems, it does not give information about MAC addresses or switch port connections, making it unsuitable for examining the MAC address table.
Similarly, the show interfaces command provides detailed information about the operational status, IP addresses, and error statistics for each network interface. It is highly useful for troubleshooting physical layer issues or monitoring traffic on a port, but it does not provide the mapping between MAC addresses and switch ports that show mac address-table offers.
Because the question specifically asks for the MAC address table on a switch, show mac address-table is the correct command. It uniquely allows administrators to view learned MAC addresses, the ports to which devices are connected, and the VLANs associated with those ports, which is essential for managing connectivity, troubleshooting Layer 2 issues, and verifying proper switch operation. None of the other commands provide this port-level MAC address information, making show mac address-table the most appropriate tool for the task.
Question 87
Which command displays the current IP address and interface status on a router or switch?
A) show ip interface brief
B) show running-config
C) show ip route
D) ping
Answer: A) show ip interface brief
Explanation
Show ip interface brief provides a concise overview of each interface’s IP address, operational status, and protocol status. It is useful for quickly verifying configuration.
Show running-config shows the active configuration, not just status.
Show ip route displays the routing table.
Ping tests connectivity, not interface configuration or status.
Because the question asks about IP addresses and status, show ip interface brief is correct.
Question 88
Which protocol provides encrypted remote access to network devices?
A) SSH
B) Telnet
C) FTP
D) HTTP
Answer: A) SSH
Explanation
SSH (Secure Shell) provides encrypted remote access, protecting credentials and data. It is widely used for secure management of routers and switches.
Telnet provides unencrypted remote access.
FTP is for file transfer, not device management.
HTTP provides web-based access but is unencrypted unless HTTPS is used.
Because the question specifies secure remote access, SSH is correct.
Question 89
Which command is used to test reachability and measure round-trip time to a host?
A) ping
B) traceroute
C) show ip route
D) show interfaces
Answer: A) ping
Explanation
Ping uses ICMP echo requests to verify connectivity to a host and measures the round-trip time of packets.
Traceroute traces the path but is primarily for path analysis, not simple reachability.
Show ip route displays routing information.
Show interfaces displays interface statistics.
Because the question asks about reachability and round-trip time, ping is correct.
Question 90
Which IPv6 address type identifies multiple interfaces for one-to-many communication?
A) Multicast
B) Unicast
C) Anycast
D) Link-Local
Answer: A) Multicast
Explanation
Multicast addresses deliver packets to all devices subscribed to a group, enabling one-to-many communication efficiently.
Unicast is one-to-one communication.
Anycast delivers packets to the nearest device in a group.
Link-local addresses are used for communication on the same link only.
Because the question specifies one-to-many communication, Multicast is correct.