Cisco 200-301 Cisco Certified Network Associate (CCNA) Exam Dumps and Practice Test Questions Set 5 Q61-75
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Question 61
Which command is used to configure an interface as a trunk port on a switch?
A) switchport mode trunk
B) switchport access vlan
C) vlan database
D) interface range
Answer: A) switchport mode trunk
Explanation
The command switchport mode trunk plays a crucial role in configuring switch ports within networks that utilize multiple VLANs. In an environment where different VLANs are created to segment traffic for security, management, or organizational purposes, it becomes essential for switches to exchange this segmented traffic between each other. A trunk port is the mechanism that enables this. When an interface is configured with switchport mode trunk, the switch port is instructed to carry traffic from multiple VLANs simultaneously. This is accomplished by tagging frames with VLAN identifiers, typically using IEEE 802.1Q encapsulation, so that each frame retains information about the VLAN to which it belongs.
In most network designs, especially in enterprise or campus environments, switches connect to each other using trunk ports rather than access ports. This ensures that all VLANs configured on one switch can be extended to another switch, maintaining consistent network segmentation throughout the infrastructure. Without trunking, each VLAN would be isolated to a single switch unless multiple physical links were used, which is highly inefficient and impractical. Therefore, switchport mode trunk becomes a fundamental command in implementing scalable and manageable VLAN architectures.
On the other hand, the command switchport access vlan is used for a completely different purpose. This command assigns a port to a single VLAN, meaning the port operates in access mode. Access ports are typically used for end devices like computers, printers, IP phones, and other client devices that belong to one specific VLAN. They do not carry tagged frames, nor do they support traffic from multiple VLANs. The switch removes any VLAN tags before forwarding traffic out an access port, ensuring the connected device receives standard Ethernet frames. While switchport access vlan is essential for connecting end hosts to the correct VLAN, it does not configure a port to carry multiple VLANs and therefore cannot function as a trunk port.
Another command, vlan database, serves an administrative purpose rather than a port configuration role. It is used to create, delete, or modify VLANs within a switch. Although VLAN creation is necessary before assigning ports or configuring trunking, the vlan database mode itself does not influence how an interface handles traffic. It simply defines which VLANs exist in the switch. Without trunking, these VLANs remain isolated locally, so the command does not contribute to enabling inter-switch VLAN communication.
The interface range command is also unrelated to configuring trunk functionality. This command allows administrators to apply configuration commands simultaneously to multiple interfaces, helping save time when configuring large groups of ports. While interface range makes bulk configuration faster and more convenient, it does not define the mode of the ports on its own. Additional commands, such as switchport mode trunk or switchport mode access, must be applied within an interface range configuration block to set specific behaviors.
Since the question specifically involves configuring a port to operate as a trunk and carry multiple VLANs across switches, the only command that accomplishes this directly is switchport mode trunk.
Question 62
Which IPv6 address is automatically assigned to an interface for local-link communication?
A) FE80::
B) FF02::1
C) 2001::
D) ::1
Answer: A) FE80::
Explanation
FE80:: addresses are link-local IPv6 addresses automatically assigned to interfaces. They allow communication within the same link without the need for a global or unique address.
FF02::1 is a multicast address for all nodes on a local link but is not assigned to an interface for communication.
2001:: addresses are global unicast addresses for internet communication.
::1 is the loopback address used for local host testing, not for link communication.
Because the question specifies local-link automatic assignment, FE80:: is correct.
Question 63
Which command is used to display the currently active configuration in a Cisco device?
A) show running-config
B) show startup-config
C) copy running-config startup-config
D) show version
Answer: A) show running-config
Explanation
The command show running-config is widely used in network administration because it displays the configuration that is actively running on a device at any given moment. This configuration is stored in RAM and represents all current operational settings applied to the device. Whenever a network engineer makes changes to interfaces, routing configurations, VLAN assignments, security parameters, or other running features, these modifications immediately appear in the running configuration. Since RAM is a volatile memory type, the running configuration is dynamic and constantly updates as changes are applied. When a device is restarted without saving the configuration, anything stored only in the running configuration is lost. For this reason, show running-config is the correct command when the goal is to view the device’s real-time, active settings exactly as they are functioning in the network.
In contrast, the command show startup-config serves a different purpose. The startup configuration is stored in NVRAM, a non-volatile memory component that retains its contents even when the device is powered off or rebooted. This startup configuration is what the device loads during boot-up. However, it may not always represent the current state of the device because administrators often make changes directly to the running configuration without immediately saving them. If the running configuration has been altered but not saved, show startup-config will display an older version of the configuration rather than the currently active one. Therefore, while the startup configuration is important for device initialization, it cannot be relied upon to show the most up-to-date operational settings.
The command copy running-config startup-config performs an essential task in network management by saving the active configuration into NVRAM. This ensures that all current settings are preserved and will be applied the next time the device boots. Although this command is necessary to prevent configuration loss, it does not display any configuration output. It only executes a save operation. Therefore, it cannot answer a question that specifically asks which command displays the running configuration. Instead, it supports configuration persistence rather than visibility.
Another commonly used command, show version, provides detailed information about the device but does not deal with configuration display. It is useful for retrieving system details such as the IOS image currently in use, device model, uptime, serial number, memory statistics, and licensing information. Although this information is helpful for troubleshooting, maintenance, and inventory management, it does not offer any insight into the active configuration of interfaces, protocols, or security settings. For this reason, show version does not fulfill the requirement of displaying the currently active configuration.
Given the differences among these commands, the only one that directly displays the active configuration stored in RAM is show running-config. It provides an exact reflection of how the device is currently operating and includes all recent changes. Therefore, when the question asks for the command that shows the currently active configuration, show running-config is the correct and most precise answer.
Question 64
Which command verifies the routing path and shows all hops to a destination?
A) traceroute
B) ping
C) show ip route
D) show interfaces
Answer: A) traceroute
Explanation
Traceroute is an essential network diagnostic tool that provides detailed insight into the path packets take from a source device to a specific destination. When a network engineer wants to understand how data travels across a network, traceroute lists each intermediate device or hop along the route. This includes routers, switches, or other network nodes that the packets encounter before reaching the final destination. By doing so, traceroute enables administrators to pinpoint potential issues such as routing loops, high latency, or misconfigured devices along a path. Each hop is displayed along with response times, which helps in analyzing performance and identifying segments of the network that may be causing delays or bottlenecks. This capability is crucial for troubleshooting complex networks, especially those that span multiple segments, subnets, or even geographically distributed locations. The detailed hop-by-hop visibility provided by traceroute allows administrators to take informed corrective actions and optimize network performance effectively.
In comparison, ping is another widely used network utility, but its purpose differs significantly from traceroute. Ping is designed to test connectivity between a source and a destination. It sends Internet Control Message Protocol (ICMP) echo request packets to a target device and waits for echo replies. The output primarily provides information about whether the destination is reachable and measures the round-trip time of packets. While ping is valuable for verifying whether a host is accessible and for measuring latency, it does not provide any information about the intermediate devices along the path. Therefore, while ping is useful for basic connectivity testing, it cannot trace the route that packets take across a network or reveal where potential issues may exist between the source and destination.
Show ip route is a command used to display the routing table on a device. It lists the known networks, associated next-hop addresses, metrics, and the interfaces used to reach those networks. This information is critical for understanding the paths a device knows and how it makes forwarding decisions. However, show ip route does not actively send packets to a destination to determine the actual route being taken in real time. It only reflects the configured or learned routes, which may not reveal transient routing problems or actual network performance along the path.
Show interfaces, on the other hand, provides information about the status, configuration, and statistics of device interfaces. It can show whether an interface is up or down, the amount of traffic transmitted and received, and error counts. While useful for interface-level troubleshooting, show interfaces does not provide visibility into network paths or the sequence of devices that packets traverse to reach a destination.
Given the specific requirement to display all the intermediate hops from a source to a destination, traceroute is uniquely suited for this purpose. It actively probes the network and returns a sequential list of each hop along with timing information, which helps identify routing issues or network segments with latency problems. Because it is the only tool among these options that shows the complete path to a destination in real time, traceroute is the correct choice for questions asking about the sequence of hops in a network.
Question 65
Which command is used to configure an IP address on a router interface?
A) ip address <IP> <subnet-mask>
B) enable
C) show ip interface brief
D) ping
Answer: A) ip address <IP> <subnet-mask>
Explanation
The ip address <IP> <subnet-mask> command assigns an IP address to a router interface. This is required for the interface to communicate on the network.
Enable switches from user mode to privileged EXEC mode but does not configure interfaces.
Show ip interface brief displays interface information but does not configure IP addresses.
Ping tests connectivity to other devices but does not assign IP addresses.
Because the question asks about configuring an IP address, ip address <IP> <subnet-mask> is correct.
Question 66
Which VLAN type carries traffic for multiple VLANs across a single link?
A) Trunk
B) Access
C) Management
D) Native
Answer: A) Trunk
Explanation
A trunk port is a fundamental component in modern network design, particularly in environments that utilize multiple VLANs to segment traffic for security, performance, or organizational purposes. The primary function of a trunk port is to carry traffic for multiple VLANs simultaneously across a single physical link between switches or other network devices. This is accomplished by tagging frames with a VLAN identifier, typically using the IEEE 802.1Q standard. By tagging frames, the receiving switch or network device can correctly identify which VLAN the traffic belongs to, ensuring that traffic from different VLANs remains logically separated even when transmitted over the same physical connection. This mechanism is critical in maintaining network segmentation and preventing traffic from different VLANs from being mixed, which could lead to security breaches or performance issues. Trunk ports are therefore essential for inter-switch communication in networks that rely on VLANs for organization and management of traffic.
In contrast, an access port serves a very different role within the network. Access ports are configured to belong to a single VLAN and are primarily used for connecting end devices such as computers, printers, IP phones, or wireless access points. Traffic sent through an access port is untagged, and the switch internally associates it with the assigned VLAN. Access ports do not carry traffic for multiple VLANs, nor do they use tagging to differentiate between VLANs. While access ports are crucial for connecting devices to the network and ensuring they are part of the correct VLAN, they do not facilitate inter-switch VLAN communication because they cannot transmit multiple VLANs simultaneously.
Another important concept is the management VLAN. The management VLAN is a dedicated VLAN used specifically for administrative access to network devices, such as switches and routers. This VLAN provides a secure path for network administrators to configure, monitor, and maintain devices without mixing management traffic with general user data. While the management VLAN is essential for security and administrative purposes, it is not designed to carry regular user or device traffic for multiple VLANs. Its purpose is limited to device management rather than enabling communication across VLANs.
The native VLAN is another concept associated with trunk ports. On a trunk link, the native VLAN is used to carry untagged frames. Any frame arriving at a trunk port without a VLAN tag is automatically associated with the native VLAN. While this ensures compatibility with devices or protocols that do not support VLAN tagging, the native VLAN is not intended to carry traffic from multiple VLANs. It functions mainly as a default or fallback VLAN for untagged traffic and does not replace the trunk port’s capability to handle multiple VLANs.
Because the question specifically refers to a port that carries traffic for multiple VLANs, the only correct choice is a trunk port. Trunk ports are uniquely capable of maintaining VLAN separation across the same physical link while allowing inter-switch communication for all configured VLANs. This makes them essential for the operation of segmented networks and ensures efficient, secure transmission of traffic between switches.
Question 67
Which type of IPv4 address allows communication to all devices in a subnet?
A) Broadcast
B) Unicast
C) Multicast
D) Anycast
Answer: A) Broadcast
Explanation
Broadcast addresses are a key concept in networking that allow a device to send a message to all other devices within a specific subnet. Unlike unicast or multicast communication, which target one device or a defined group of devices, broadcast communication ensures that every host within the subnet receives the message. This one-to-all communication mechanism is essential for several foundational network operations. For example, Address Resolution Protocol, or ARP, relies heavily on broadcast messages to map IP addresses to MAC addresses. When a device needs to determine the MAC address associated with a particular IP address, it sends an ARP request to the broadcast address of the subnet, ensuring that all devices receive the query. The device that owns the requested IP responds directly to the sender, allowing communication to proceed. This process would not be possible without broadcast communication because unicast or multicast methods would not reach all devices by default.
Broadcast is also used for network-wide announcements and other administrative purposes. Certain protocols, such as Dynamic Host Configuration Protocol in its discovery phase, may use broadcast messages to locate available servers within a local network. Similarly, routers or switches can rely on broadcast frames to inform all devices about certain network events or changes, such as topology updates or alert messages. By reaching every device within the subnet simultaneously, broadcast messages help maintain network awareness and consistency, ensuring that all hosts receive critical information in a timely manner. This is particularly important in environments where devices frequently join or leave the network, or when network configurations are dynamic.
In contrast, unicast addressing is intended for one-to-one communication. A unicast packet is sent from a single sender to a single recipient. While this approach is suitable for most day-to-day network interactions, such as web browsing or email delivery, it does not provide a mechanism for simultaneously reaching every host in a subnet. Unicast communication is efficient when addressing a specific device, but it cannot fulfill the need for one-to-all communication because it requires a separate transmission for each intended recipient, which would be impractical for network-wide announcements.
Multicast addresses are designed for one-to-many communication, where packets are delivered only to devices that have explicitly subscribed to a multicast group. This is commonly used for streaming media, video conferencing, or other applications where only a subset of devices requires the data. While multicast is efficient for reducing unnecessary traffic to uninterested hosts, it does not reach all devices in a subnet unless every device subscribes to the group, so it does not provide true one-to-all communication.
Anycast addressing is a technique where multiple devices share the same address, and packets are routed to the nearest device based on routing metrics. Anycast is used for optimizing resource access, such as querying the closest DNS server, but it only reaches one device, not all devices, and therefore cannot be used for network-wide delivery.
Since the question specifically focuses on delivering packets to all devices in a subnet, the correct choice is broadcast. Broadcast ensures that every host within the subnet receives the information simultaneously, making it indispensable for tasks like ARP, DHCP discovery, and network-wide announcements.
Question 68
Which command is used to view interface error statistics on a switch?
A) show interfaces
B) show ip route
C) show arp
D) ping
Answer: A) show interfaces
Explanation
The show interfaces command is an essential diagnostic tool used by network administrators to monitor the status and performance of network interfaces on a switch, router, or other network device. This command provides detailed information about each interface, including its operational state, protocol status, link speed, duplex settings, and the number of packets transmitted and received. One of the most critical aspects of the information provided by show interfaces is the reporting of errors, which can include collisions, cyclic redundancy check (CRC) errors, input errors, output errors, packet drops, and other anomalies. Monitoring these error statistics is crucial for identifying and troubleshooting problems at the physical and data link layers, helping administrators maintain network reliability and performance. By analyzing interface error counts, administrators can detect faulty cables, failing hardware, configuration mismatches, or congestion issues that could impact network communication.
Collisions occur when two devices transmit on the same network segment simultaneously, which is more common in half-duplex Ethernet environments. CRC errors indicate data corruption during transmission, often caused by noise, faulty cabling, or interference. Input and output errors reflect issues in receiving or sending frames and can signal problems with hardware or interface settings. Packet drops may result from congestion, buffer overflows, or misconfigurations. By using show interfaces, administrators can pinpoint which interfaces are experiencing these issues, allowing for timely corrective actions, such as replacing cables, adjusting duplex settings, or reconfiguring the interface. The comprehensive statistics provided by this command make it a powerful tool for maintaining network stability and diagnosing performance issues.
In comparison, show ip route provides information about the routing table, including directly connected networks, static routes, and routes learned through dynamic routing protocols. While it is invaluable for troubleshooting Layer 3 connectivity and verifying that devices have proper routing paths, it does not provide any data about interface errors, collisions, or packet drops. Therefore, show ip route is not suitable for addressing problems at the physical or data link layers.
Similarly, the show arp command displays the Address Resolution Protocol cache, which maps IP addresses to MAC addresses on the local network. This information is useful for resolving IP-to-MAC relationships and diagnosing communication issues related to address resolution, but it does not provide statistics about interface performance or errors. Show arp cannot help identify problems such as CRC errors, collisions, or packet drops, making it inappropriate for the task of monitoring interface health.
Ping is another commonly used network troubleshooting tool that tests connectivity between two devices by sending ICMP echo requests and measuring response times. While ping can indicate whether a host is reachable and provide round-trip latency statistics, it does not offer visibility into the performance or error statistics of the interfaces along the path. Ping cannot reveal hardware-level or interface-specific issues such as packet drops or CRC errors, which are critical for diagnosing problems at Layer 1 and Layer 2.
Because the question specifically requires viewing detailed interface error statistics to troubleshoot physical or data link issues, the correct command is show interfaces. It is the only command among the options that provides comprehensive, real-time information about interface status, errors, and performance, making it essential for effective network diagnostics and maintenance.
Question 69
Which type of IPv6 address identifies a single interface for one-to-one communication?
A) Unicast
B) Multicast
C) Anycast
D) Link-Local
Answer: A) Unicast
Explanation
Unicast addressing is one of the fundamental communication methods used in networking, designed to facilitate direct, one-to-one communication between devices. When a device sends a packet to a unicast address, that packet is intended for a single specific recipient and is delivered only to that device. This approach ensures that the data reaches the correct destination without being shared with other devices on the network. Unicast is the most common type of communication used in networks because most everyday operations, such as web browsing, email transmission, and file transfers, involve a single sender transmitting information to a specific receiver. Each unicast transmission requires a unique destination address, and the network uses routing or switching mechanisms to ensure that packets are delivered accurately to the intended interface.
One of the key advantages of unicast communication is its precision. Since packets are sent to a specific device, there is no unnecessary consumption of bandwidth by other devices that are not intended to receive the data. This makes unicast efficient for point-to-point communications where reliability and accuracy are important. Devices along the network path use the destination address to forward the packet through switches and routers, ensuring that it reaches only the correct recipient. Unicast also allows for acknowledgment and error-checking mechanisms, providing more reliable communication in comparison to broadcast or multicast methods, where packets may be received by multiple devices simultaneously.
In contrast, multicast addresses are designed for one-to-many communication. A single packet sent to a multicast address is delivered only to devices that have explicitly subscribed to that multicast group. This is commonly used for streaming media, video conferencing, or sending updates to multiple devices without flooding the entire network. While multicast is efficient for group communication, it does not provide one-to-one delivery, as packets may be received by multiple devices depending on their subscription. Therefore, multicast does not fulfill the requirement for direct, individual communication.
Anycast addressing is another communication method but serves a different purpose. In anycast, multiple devices share the same IP address, and the network delivers a packet to the nearest or best-performing device based on routing metrics. Anycast is often used for load balancing or directing users to the closest server, such as in DNS or content delivery networks. Despite involving multiple devices sharing the same address, only one device receives the packet, making it unsuitable for general one-to-one communication in typical networking scenarios.
Link-local addresses are used for communication within a single local link, such as within a single Ethernet segment. These addresses allow devices to communicate without requiring globally routable addresses and are primarily used for automatic address configuration or network protocol operations within the local segment. Link-local addresses do not provide standard one-to-one communication across broader networks because they are limited to a local scope.
Since the question specifically focuses on one-to-one communication, unicast is the correct choice. It ensures that data sent from a sender reaches only the intended recipient, providing precise and efficient delivery. Unlike multicast, anycast, or link-local addressing, unicast uniquely supports direct communication between individual devices.
Question 70
Which protocol translates hostnames into IP addresses?
A) DNS
B) DHCP
C) ARP
D) ICMP
Answer: A) DNS
Explanation
The Domain Name System, commonly known as DNS, is a critical component of modern networking that enables the translation of human-readable hostnames into IP addresses. This functionality allows users to access websites, servers, and other network resources using easy-to-remember names instead of numeric IP addresses. For example, a user can type a web address such as www.example.com into a browser, and DNS will resolve that name to the corresponding IP address needed for communication over the internet or within a private network. Without DNS, users would need to memorize numeric IP addresses for every resource they want to access, which is not practical in today’s expansive network environments. DNS therefore plays a fundamental role in simplifying network navigation and improving usability.
DNS operates through a hierarchical system of servers, including root servers, top-level domain servers, and authoritative name servers. When a client queries a DNS server for a hostname, the request may be resolved locally if the server has the information cached, or it may be forwarded to other servers in the hierarchy to locate the authoritative answer. Once the DNS server retrieves the IP address associated with the hostname, it returns this information to the client, allowing the device to establish a connection to the target resource. This process ensures efficient and scalable resolution, even across large and complex networks. DNS also supports various record types, such as A records for IPv4 addresses, AAAA records for IPv6 addresses, MX records for mail servers, and CNAME records for aliasing, which allows for flexibility and detailed network management.
In contrast, DHCP, or Dynamic Host Configuration Protocol, provides automatic assignment of IP addresses, subnet masks, gateways, and other configuration parameters to devices joining a network. While DHCP is essential for ensuring devices have valid network settings and preventing address conflicts, it does not perform the task of translating hostnames into IP addresses. DHCP enables devices to participate in the network but does not assist users or applications in locating resources by name.
ARP, or Address Resolution Protocol, is another protocol with a different function. ARP maps IP addresses to MAC addresses within a local network segment, allowing devices to deliver frames over the data-link layer. While ARP is critical for local communication between devices, it does not resolve human-readable hostnames into IP addresses, and its scope is limited to Layer 2 network operations. ARP cannot provide DNS-like services for locating resources by name.
ICMP, or Internet Control Message Protocol, is used for network diagnostics and error reporting. Tools such as ping and traceroute rely on ICMP to test connectivity, measure response times, and identify routing problems. Although ICMP is valuable for troubleshooting, it does not perform hostname resolution or provide a mechanism for translating names into IP addresses.
Because the requirement specifically asks for the translation of hostnames to IP addresses, DNS is the correct solution. It uniquely fulfills this purpose, enabling users and applications to connect to network resources using human-friendly names while abstracting the underlying numeric addressing required for packet delivery. No other protocol listed provides this functionality, making DNS indispensable for name resolution in both local and global networks.
Question 71
Which protocol is used to dynamically assign IP addresses to hosts?
A) DHCP
B) DNS
C) ARP
D) ICMP
Answer: A) DHCP
Explanation
Dynamic Host Configuration Protocol, commonly known as DHCP, is a critical network protocol that automates the assignment of IP addresses and other essential network configuration parameters to devices on a network. When a device connects to a network, DHCP ensures that it receives a valid IP address, a subnet mask, a default gateway, and DNS server information without requiring manual configuration by a network administrator or the end user. This automation simplifies network management, particularly in large networks with hundreds or thousands of devices, where manually assigning IP addresses would be time-consuming, prone to errors, and difficult to maintain. By automatically providing configuration details, DHCP helps prevent issues such as duplicate IP addresses, misconfigured subnet masks, or incorrect gateway information, which could otherwise disrupt network communication.
The process by which DHCP operates involves a series of standardized message exchanges between a client and a DHCP server. When a device connects to the network, it sends a DHCP discovery message to locate available servers. The DHCP server responds with an offer that includes an available IP address and other configuration parameters. The client then requests the offered address, and the server confirms the assignment through an acknowledgment message. This sequence, often referred to as the DHCP handshake, ensures that devices receive the necessary configuration information to participate on the network immediately. DHCP also supports lease times, which determine how long a device can use an assigned IP address. Once the lease expires, the IP address may be renewed or reassigned, ensuring efficient utilization of the available address space.
In contrast, the Domain Name System, or DNS, serves an entirely different purpose. DNS is responsible for translating human-readable hostnames into IP addresses, allowing users to access websites, servers, and network resources without remembering numerical addresses. While DNS is essential for enabling user-friendly network navigation and connectivity, it does not assign IP addresses to devices, and therefore cannot fulfill the role of DHCP in automating network configuration.
Similarly, Address Resolution Protocol, or ARP, operates at a different layer of the network. ARP is responsible for mapping IP addresses to MAC addresses within a local network segment. This mapping is necessary for devices to deliver packets on the local data-link layer, but ARP does not provide IP addresses, subnet masks, gateways, or DNS information. ARP assists with local communication between devices, but it does not perform the automated assignment of network configuration parameters.
Internet Control Message Protocol, or ICMP, is also unrelated to IP assignment. ICMP is used primarily for network diagnostics and error reporting, enabling tools like ping and traceroute to measure connectivity, detect unreachable devices, and identify routing issues. While ICMP provides valuable information for troubleshooting network problems, it does not assign addresses or configure devices for network participation.
Because the question specifically focuses on the automatic assignment of IP addresses and related network configuration, DHCP is the correct answer. It uniquely provides dynamic configuration, reduces administrative effort, and ensures devices can communicate effectively on the network, fulfilling a function that no other protocol mentioned can perform.
Question 72
Which type of cable is used to connect a PC to a switch port?
A) Straight-through
B) Crossover
C) Rollover
D) Fiber patch
Answer: A) Straight-through
Explanation
Ping is a widely used network diagnostic tool that verifies connectivity between a source device and a remote host on a network. It operates by sending Internet Control Message Protocol (ICMP) echo request packets to the target device and waiting for echo reply responses. When the target device receives an echo request, it responds with an echo reply, confirming that the device is reachable and that packets can traverse the network successfully. In addition to verifying connectivity, ping also measures the round-trip time, which indicates the delay between sending a packet and receiving the response. This information helps network administrators assess the responsiveness of the network and identify potential performance issues such as latency or packet loss. Ping is simple, fast, and highly effective, making it one of the most fundamental tools for network troubleshooting.
The primary advantage of ping is its ability to quickly determine whether a remote device is operational and accessible. By issuing a series of echo requests, administrators can confirm that network paths are functioning correctly and detect intermittent connectivity problems. Ping is commonly used during initial network setup, after configuration changes, or when diagnosing issues reported by users. If a ping fails, it may indicate problems such as a misconfigured IP address, a disconnected cable, a downed interface, or a routing issue. Network engineers often use ping in combination with other tools to narrow down the source of connectivity failures and verify the success of corrective actions.
Traceroute, on the other hand, serves a different purpose. While it also sends ICMP packets to a remote host, its primary function is to trace the path that packets take through the network, showing each hop along the route to the destination. Traceroute provides valuable information about routing paths, intermediate devices, and potential points of delay, but it is focused on path diagnostics rather than simple connectivity verification. Although traceroute can confirm whether a host is reachable indirectly, it is more complex than ping and is not optimized for quickly testing basic connectivity.
The show ip route command provides insight into a device’s routing table, displaying known network destinations, next-hop addresses, and outgoing interfaces. While this information is crucial for understanding how a network forwards packets, it does not directly test whether a remote host can be reached. Routing tables indicate potential paths, but they do not confirm the operational status of the network or the availability of the destination host, which is why show ip route cannot replace ping for connectivity testing.
Similarly, show interfaces is a diagnostic command that displays the status and statistics of a device’s network interfaces, including errors, packet counts, and operational state. This command is valuable for troubleshooting physical and data-link layer issues, such as collisions, CRC errors, or interface failures. However, it does not provide information about the reachability of remote hosts or whether packets successfully traverse the network.
Since the question specifically requires verifying connectivity to a remote host, ping is the correct tool. It directly tests the ability of a device to communicate across a network, provides round-trip timing information, and quickly identifies reachability problems. Unlike traceroute, show ip route, or show interfaces, ping is designed for simple, effective connectivity verification, making it the most appropriate choice for this task.
Question 73
Which protocol is used to resolve MAC addresses from known IP addresses?
A) ARP
B) DNS
C) DHCP
D) ICMP
Answer: A) ARP
Explanation
Address Resolution Protocol, commonly known as ARP, is a fundamental protocol used in networking to associate IP addresses with their corresponding physical hardware addresses, also called MAC addresses. In a local area network, devices communicate using both Layer 3 addresses (IP addresses) and Layer 2 addresses (MAC addresses). While IP addresses are used for logical routing and identifying devices across networks, MAC addresses are essential for delivering frames over the physical network. ARP serves as the bridge between these two addressing schemes, allowing devices to determine the MAC address of a host when its IP address is known. This functionality is critical for ensuring that packets are delivered accurately within a local network segment.
When a device needs to communicate with another device on the same subnet, it first checks its ARP table, which stores recently learned IP-to-MAC mappings. If the mapping is not already known, the device sends an ARP request as a broadcast message to all devices on the local network. This request asks which device owns the specific IP address. The device that matches the requested IP responds with its MAC address, which the requesting device then stores in its ARP table for future use. This process allows communication to continue efficiently, minimizing the need for repeated broadcasts and ensuring that Ethernet frames can reach the correct destination hardware interface.
While ARP focuses specifically on mapping IP addresses to MAC addresses, other protocols handle different aspects of networking and do not perform this function. The Domain Name System, or DNS, for instance, is used to resolve human-readable hostnames into IP addresses. DNS allows users to access websites or services using names instead of numerical IP addresses. However, DNS does not provide any information about the physical addresses of devices, nor does it facilitate the delivery of frames at the data link layer. Its role is entirely at the logical layer for name resolution.
Dynamic Host Configuration Protocol, or DHCP, is another protocol often used in local networks, but its purpose is different from ARP. DHCP automatically assigns IP addresses, subnet masks, default gateways, and DNS server information to devices on a network. While DHCP ensures that devices receive valid IP addresses and other configuration parameters, it does not perform the task of determining MAC addresses corresponding to those IP addresses. DHCP handles dynamic allocation of network configuration but cannot map logical addresses to physical hardware addresses for packet delivery.
Internet Control Message Protocol, or ICMP, provides diagnostic and error-reporting functions in IP networks. Tools such as ping and traceroute rely on ICMP to test connectivity, measure latency, and report network issues. ICMP is valuable for troubleshooting and understanding network behavior, but it does not interact with MAC addresses or resolve IP-to-MAC mappings. Its role is limited to monitoring and reporting at the network layer.
Because the requirement is specifically to map IP addresses to MAC addresses within a local network, ARP is the correct protocol. It is uniquely designed to provide this functionality, enabling devices to translate logical addresses into physical addresses necessary for accurate delivery of frames across the network. None of the other protocols mentioned, including DNS, DHCP, or ICMP, perform this function, making ARP indispensable for local network communication and data delivery.
Question 74
Which protocol provides secure remote access to network devices?
A) SSH
B) Telnet
C) HTTP
D) FTP
Answer: A) SSH
Explanation
Secure Shell, commonly known as SSH, is a network protocol that provides encrypted remote access to network devices, such as routers, switches, and servers. One of the primary advantages of SSH is its ability to secure communications by encrypting both authentication credentials and transmitted data, preventing eavesdropping, tampering, or interception by unauthorized parties. This encryption ensures that sensitive information, including usernames, passwords, and configuration commands, is protected while being transmitted across potentially insecure networks. SSH is widely used in enterprise and data center environments to manage devices remotely, perform administrative tasks, and troubleshoot network issues without compromising security. Its adoption has become standard practice for secure management of network infrastructure.
In contrast, Telnet is an older protocol that also provides remote access to network devices, but it transmits all data, including credentials, in clear text. This lack of encryption makes Telnet highly vulnerable to interception and attack, particularly when used over public or untrusted networks. Any attacker capable of monitoring the network traffic can easily capture login information or sensitive commands, which could lead to unauthorized access and compromise of network devices. Due to these security risks, Telnet is largely considered obsolete for modern network management and is replaced by secure alternatives like SSH in most organizations.
HTTP, or Hypertext Transfer Protocol, is primarily used for accessing web pages and web-based management interfaces on devices. Standard HTTP communication is unencrypted, meaning that data sent between a client and a web server can be intercepted and read by third parties. While HTTP can be used to remotely manage network devices through a browser interface, it does not meet the security requirements for protecting sensitive administrative access unless it is specifically upgraded to HTTPS. HTTPS, or HTTP Secure, adds encryption using SSL/TLS, but plain HTTP alone is not sufficient for secure remote access.
FTP, or File Transfer Protocol, is designed for transferring files between devices on a network. Standard FTP transmits both credentials and file data in clear text, similar to Telnet, and is therefore vulnerable to interception and attack. While FTP can be useful for moving configuration files, software updates, or other data to network devices, it does not provide secure interactive access for device management. Secure alternatives like SFTP or FTPS exist, which add encryption, but plain FTP does not satisfy the requirement for secure remote access to perform administrative tasks.
SSH, by contrast, was specifically designed to replace insecure protocols like Telnet while providing strong encryption, authentication, and data integrity. It uses public key cryptography and secure session establishment to ensure that communications are protected from eavesdropping and tampering. Administrators can use SSH to execute commands, configure devices, and monitor network performance with confidence that sensitive information remains secure.
Because the requirement in this scenario specifies secure remote access to network devices, SSH is the correct choice. It uniquely combines the ability to manage devices remotely with strong encryption, ensuring that credentials and configuration data are protected. Other protocols, such as Telnet, HTTP, and FTP, either lack encryption or are designed for different purposes and therefore do not meet the security requirement. SSH remains the standard solution for secure administrative access in modern networks.
Question 75
Which type of IPv6 address is used for one-to-nearest communication among multiple devices?
A) Anycast
B) Unicast
C) Multicast
D) Link-Local
Answer: A) Anycast
Explanation
Anycast addresses are assigned to multiple devices, and packets sent to an anycast address are delivered to the nearest device based on routing metrics. This optimizes service delivery and load balancing.
Unicast addresses are for one-to-one communication.
Multicast addresses deliver packets to all subscribers in a group.
Link-local addresses are used for communication within the same link only.
Because the question asks for one-to-nearest communication, Anycast is correct.