Cisco 200-301 Cisco Certified Network Associate (CCNA) Exam Dumps and Practice Test Questions Set 4 Q46-60

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Question 46

Which command is used to configure a default gateway on a Cisco switch?

A) ip default-gateway <IP>
B) ip route <IP>
C) show ip route
D) enable

Answer: A) ip default-gateway <IP>

Explanation

The ip default-gateway <IP> command configures the default gateway on a switch, allowing it to communicate with devices outside its local subnet. Without a default gateway, the switch cannot reach remote networks for management or communication purposes.

The ip route <IP> command is used on routers to create static routes, not for simple gateway assignment on a switch.

Show ip route displays the routing table, which provides information but does not configure a default gateway.

Enable switches from user mode to privileged EXEC mode but does not configure any network parameters.

Because the question asks specifically about a switch’s gateway configuration, ip default-gateway <IP> is correct.

Question 47

Which type of NAT translates multiple private IP addresses to a single public IP address?

A) PAT
B) Static NAT
C) Dynamic NAT
D) DNS

Answer: A) PAT

Explanation

Port Address Translation, commonly known as PAT, is a specific type of Network Address Translation (NAT) that enables multiple devices on a private network to access external networks using a single public IP address. In modern networks, particularly in home and small office environments, the availability of public IPv4 addresses is limited. PAT addresses this limitation by allowing numerous internal devices, each with a private IP address, to share a single public IP when communicating with the internet. This is achieved by translating the private IP addresses into the public IP address while differentiating each session or connection using unique port numbers.

When an internal device sends traffic to an external destination, PAT replaces the source IP address in the packet with the public IP of the NAT device and assigns a unique source port number. The combination of the public IP and port number allows the NAT device to track multiple connections simultaneously. When a reply packet returns from the external network, PAT uses the port number information to correctly forward the traffic to the originating private IP address. This process ensures that multiple devices can access the internet concurrently without requiring a separate public IP for each device, significantly conserving public IP address resources and simplifying network management.

It is important to contrast PAT with other NAT techniques to understand why PAT is the correct choice in scenarios where multiple private addresses need to share a single public IP. Static NAT, for example, maps a single private IP address to a single public IP address. This approach is useful for devices that need consistent external accessibility, such as web servers or mail servers. However, static NAT cannot accommodate scenarios where many internal devices need to communicate externally through a single public IP simultaneously, making it unsuitable for typical home or small office networks.

Dynamic NAT provides another method for mapping private IP addresses to public IP addresses. In dynamic NAT, a pool of available public IP addresses is maintained, and internal devices are assigned a public IP temporarily from this pool when they initiate external connections. While dynamic NAT allows multiple internal devices to communicate externally, it does not allow multiple devices to share the same public IP simultaneously. Once the pool of public IP addresses is exhausted, additional internal devices cannot establish connections, which limits scalability.

Domain Name System, or DNS, is unrelated to address translation. DNS is responsible for resolving human-readable hostnames into IP addresses, enabling users to access websites and services using familiar names instead of numeric IP addresses. It does not perform network address translation, mapping private IP addresses to public IPs, or tracking multiple internal sessions.

Given the need to allow multiple internal devices to share a single public IP address while maintaining unique sessions for each connection, Port Address Translation is the correct solution. By using unique port numbers to differentiate connections, PAT efficiently conserves public IP addresses, supports scalable internet access for multiple devices, and is widely deployed in home networks, small offices, and enterprise edge routers. It remains a cornerstone technology for managing IPv4 address scarcity and enabling seamless connectivity across private and public networks.

Question 48

Which IPv6 address type is used for all nodes on a link?

A) FF02::1
B) FE80::
C) 2001::
D) FF00::

Answer: A) FF02::1

Explanation

FF02::1 is a multicast address that targets all nodes on a local link. Any packet sent to this address is received by all IPv6 devices on the link.

FE80:: addresses are link-local addresses assigned to each interface, used for communication within the same link but not for all nodes simultaneously.

2001:: addresses are global unicast addresses used for internet communication, not for local multicast.

FF00:: is the general multicast address prefix; specific addresses like FF02::1 are used for all-link communication.

Because the question asks for addressing all devices on a link, FF02::1 is correct.

Question 49

Which layer of the OSI model is responsible for flow control and sequencing?

A) Transport
B) Network
C) Data Link
D) Session

Answer: A) Transport

Explanation

The Transport layer, which occupies Layer 4 of the OSI model, plays a crucial role in ensuring reliable end-to-end communication between devices on a network. Its primary responsibility is to provide mechanisms that guarantee that data sent from one device is received accurately, completely, and in the correct order by the intended recipient. Unlike lower layers, which handle delivery within a single network segment, the Transport layer oversees the entire journey of data between source and destination applications, making it essential for maintaining reliable communications in complex network environments.

One of the key functions of the Transport layer is flow control. Flow control ensures that a sender does not overwhelm a receiver with more data than it can process at a time. Without flow control, a fast sender could inundate a slower receiver, leading to buffer overflows, data loss, and the need for retransmission. Transport layer protocols, such as the Transmission Control Protocol (TCP), use flow control techniques like sliding windows, where the sender can transmit a limited number of segments before needing an acknowledgment from the receiver. This mechanism ensures that both sender and receiver operate at compatible speeds, maintaining efficient and orderly data transfer.

In addition to flow control, the Transport layer provides sequencing of data segments. When large amounts of data are transmitted, they are divided into smaller segments for efficient delivery. TCP assigns a sequence number to each segment so that the receiving device can reassemble them in the correct order, even if the segments arrive out of sequence due to varying network paths or delays. This sequencing ensures that the application at the receiving end receives a coherent, correctly ordered stream of data, preserving the integrity and meaning of the transmitted information.

It is important to differentiate the Transport layer’s functions from those of other layers. The Network layer, for example, is responsible for logical addressing and routing packets from the source device to the destination device across multiple networks. While it determines the path data takes, it does not manage end-to-end flow control or segment sequencing. Similarly, the Data Link layer operates at a lower level to provide reliable delivery of frames within a single network segment. It can implement error detection and local flow control, but its scope is limited to a single link rather than the entire communication path between source and destination.

The Session layer, which operates above the Transport layer, manages communication sessions between applications, handling tasks such as session initiation, maintenance, and termination. Although it organizes interactions between applications, it does not provide mechanisms for segment sequencing or end-to-end flow control.

Given the requirement to ensure both flow control and proper sequencing of data across the entire communication path between devices, the Transport layer is the correct layer responsible for these functions. By implementing flow control and sequencing, it guarantees reliable, orderly, and efficient data delivery, enabling applications to communicate accurately and effectively over potentially complex and unreliable networks.

Question 50

Which protocol is used for time synchronization on network devices?

A) NTP
B) DHCP
C) SNMP
D) ICMP

Answer: A) NTP

Explanation

Network Time Protocol, commonly referred to as NTP, is a fundamental protocol used to synchronize the clocks of devices across a network. Accurate timekeeping is critical in modern networks because many network functions rely on precise timestamps. For instance, logs generated by network devices, servers, and applications require accurate timestamps to allow administrators to trace events, identify issues, and perform audits effectively. Authentication protocols, such as Kerberos, also rely on synchronized clocks to prevent replay attacks and ensure that security credentials remain valid. Furthermore, distributed systems, applications, and databases that operate across multiple devices require time consistency to coordinate operations and maintain data integrity. Without proper synchronization, network operations can become unreliable, logs may be inconsistent, and troubleshooting becomes challenging. NTP addresses these issues by providing a standardized method for devices to maintain accurate and consistent time.

NTP works by enabling devices, called clients, to communicate with NTP servers, which serve as authoritative sources of time. These servers may synchronize their clocks with highly accurate reference clocks, such as atomic clocks or GPS time sources, ensuring a high degree of precision. When a device queries an NTP server, it calculates the offset between its local clock and the server’s clock, taking into account the network delay. The client then adjusts its local clock gradually to align with the server’s time. This process occurs continuously, allowing devices to maintain synchronization even in the presence of clock drift or varying network latency. Modern NTP implementations can achieve synchronization accuracy within milliseconds over typical network connections.

It is important to distinguish NTP from other network protocols that are sometimes confused with time-related functions but do not perform synchronization. Dynamic Host Configuration Protocol, or DHCP, automatically assigns IP addresses, subnet masks, default gateways, and DNS server information to devices. While DHCP simplifies network configuration and management, it does not provide any mechanism for synchronizing clocks across devices.

Simple Network Management Protocol, or SNMP, is widely used for monitoring and managing network devices. It collects device metrics, monitors performance, and enables remote configuration. However, SNMP does not synchronize clocks or ensure time consistency, and relying solely on SNMP does not guarantee accurate timestamps across devices.

The Internet Control Message Protocol, or ICMP, provides network diagnostic and error reporting capabilities, such as ping and traceroute. While ICMP is useful for verifying connectivity and measuring latency, it does not perform time synchronization or maintain consistent clocks on network devices.

Considering the requirement to synchronize device clocks accurately for logging, authentication, and coordinated operations across a network, Network Time Protocol is the correct solution. By continuously aligning device clocks with reliable time sources and accounting for network delays, NTP ensures that all devices in the network maintain precise and consistent time, which is essential for secure, reliable, and well-coordinated network operations.

Question 51

Which command displays the current MAC address table of a switch?

A) show mac address-table
B) show arp
C) show ip route D) show running-config

Answer: A) show mac address-table

Explanation

The show mac address-table command is a fundamental tool used in managing and troubleshooting Layer 2 networks. This command provides a complete list of all MAC addresses that a switch has learned, along with the specific switch ports through which these addresses were discovered. Each entry in the MAC address table indicates the hardware address of a device and the interface associated with it, allowing administrators to determine exactly where devices are connected in the network. By examining the MAC address table, network engineers can understand the layout of the network at the data-link layer, verify connectivity, and troubleshoot issues such as misconfigured ports, unauthorized devices, or network loops. The command is especially useful in environments with numerous switches and endpoints, where keeping track of physical device locations manually would be impractical. With the information provided by the MAC address table, administrators can ensure that traffic is being forwarded efficiently, that devices are connecting to the intended ports, and that the switch is functioning properly in terms of learning and aging MAC addresses.

In contrast, the show arp command serves a different purpose. ARP, or Address Resolution Protocol, maps IP addresses to MAC addresses on a local network. While this is crucial for devices to communicate within the same subnet, show arp only provides a mapping of Layer 3 addresses to Layer 2 hardware addresses. It does not provide the broader context of which switch ports these devices are connected to, nor does it list all MAC addresses learned by the switch. Therefore, show arp is more useful for troubleshooting IP connectivity issues rather than examining the physical connection and switching paths of devices.

Similarly, the show ip route command provides information about Layer 3 routing tables. This command displays known network destinations, the associated next-hop addresses, and the outgoing interfaces used to reach them. While it is an essential tool for verifying network paths and diagnosing routing issues, it has no visibility into the MAC addresses learned by a switch or which ports those addresses are associated with. It focuses entirely on network layer paths rather than data-link layer connectivity.

The show running-config command, on the other hand, shows the current configuration of a switch or router, including interface settings, VLAN assignments, IP addresses, security policies, and protocol configurations. While this information is valuable for verifying static configurations and settings applied to the device, it does not include dynamic information about MAC addresses that have been learned during operation. Therefore, it cannot be used to identify where devices are physically connected on the switch.

Because the question specifically asks for information about the MAC address table, the show mac address-table command is the correct choice. It uniquely provides a dynamic, real-time view of all MAC addresses known to the switch and the ports through which they were learned, enabling administrators to monitor, troubleshoot, and manage the network at the Layer 2 level. None of the other commands listed provide this specific functionality, making show mac address-table the only appropriate tool for the task.

Question 52

Which protocol is used to remotely monitor network devices?

A) SNMP
B) FTP
C) Telnet
D) HTTP

Answer: A) SNMP

Explanation

Simple Network Management Protocol, commonly known as SNMP, is a widely adopted protocol that enables network administrators to remotely monitor, manage, and gather information from various network devices. These devices can include routers, switches, firewalls, servers, printers, and many other network-connected components. SNMP provides a standardized method for collecting operational data, such as bandwidth usage, device uptime, error rates, CPU and memory consumption, interface statistics, and overall health indicators. By using SNMP, organizations can achieve centralized visibility and control over their network infrastructure, making it easier to maintain optimal performance, detect issues early, and respond quickly to potential failures.

One of the key strengths of SNMP is its ability to generate alerts or notifications known as traps. These alerts are sent automatically from devices to management systems when certain thresholds are exceeded or when specific events occur. This proactive capability allows administrators to identify problems in real time, sometimes even before they affect end users. SNMP also enables basic configuration tasks on supported devices, allowing certain settings to be adjusted remotely. Although modern management systems often rely on more advanced protocols, SNMP remains a foundational tool due to its simplicity, reliability, and nearly universal support across network hardware.

In contrast, FTP, or File Transfer Protocol, is designed specifically for transferring files between systems over a network. While FTP can move data from one location to another, it does not provide any tools or mechanisms for monitoring device performance, gathering operational statistics, or issuing alerts. It lacks any built-in functionality for observing the state of hardware or software components. Because of this, FTP cannot serve as a network monitoring solution and does not meet the requirements for managing network health or performance.

Telnet is another protocol that often appears in discussions about remote device access. It allows administrators to connect to network equipment and perform configuration tasks through a command-line interface. However, its role is limited to interactive sessions, and it does not include features for centralized monitoring or automated data collection. Telnet provides access to devices but does not support the systematic gathering of performance metrics. Additionally, Telnet transmits data in plain text, making it less secure compared to more modern protocols like SSH.

HTTP, or Hypertext Transfer Protocol, can provide a web-based interface for device management. Many network devices include built-in web dashboards that allow administrators to view configuration settings or check certain status indicators. While this can be convenient, HTTP is not a dedicated monitoring protocol. It does not inherently support continuous data collection, automated alerts, or standardized metrics across different types of devices. Any monitoring functionality delivered through a web interface is usually vendor-specific and not suitable for consistent, centralized management.

Because the question specifically emphasizes the need for network monitoring, the correct choice is SNMP. It uniquely fulfills the requirements of collecting statistics, enabling centralized oversight, and supporting automated alerting. SNMP remains the primary and most effective protocol for monitoring network devices across diverse environments.

Question 53

Which routing protocol is classless and supports VLSM?

A) OSPF
B) RIP version 1
C) IGRP
D) IPX

Answer: A) OSPF

Explanation

Open Shortest Path First, commonly known as OSPF, is a widely used classless link-state routing protocol designed to operate efficiently in medium to large enterprise networks. Being classless means that OSPF fully supports Variable Length Subnet Masking, or VLSM, which allows network administrators to create subnets of varying sizes based on the specific requirements of different segments within a network. This flexibility improves overall IP address utilization, helps conserve address space, and enables more efficient network design. OSPF also uses a hierarchical structure with areas, which enhances scalability and reduces overhead by limiting the size of routing tables and minimizing the propagation of routing updates. Because OSPF is a link-state protocol, it builds a complete map of the network topology and uses algorithms such as Dijkstra’s Shortest Path First to determine the most efficient route to each destination. This method leads to rapid convergence and improves stability compared to many distance-vector protocols.

RIP version 1, or Routing Information Protocol version 1, is an older distance-vector protocol that relies on hop count as its primary metric. One of the major limitations of RIP version 1 is that it is classful, meaning it does not carry subnet mask information in its routing updates. As a result, it cannot support VLSM or Classless Inter-Domain Routing. This restriction makes RIP version 1 suitable only for very small networks and severely limits its ability to handle modern addressing needs. Without VLSM support, network designers cannot create subnets of different sizes to optimize address allocations, which often leads to wasted IP space and inefficient network structures. Because of these constraints, RIP version 1 is no longer widely used in contemporary network environments.

IGRP, or Interior Gateway Routing Protocol, is another legacy distance-vector routing protocol originally developed by Cisco. Like RIP version 1, IGRP is classful and therefore unable to support VLSM. It was designed to improve scalability and overcome some of RIP’s limitations, such as its small hop-count threshold. Despite these improvements, the lack of subnet mask information in IGRP routing advertisements means that it cannot participate in classless routing schemes. This makes it unsuitable for modern networks where flexible addressing techniques are essential. IGRP has been largely replaced by more advanced protocols, including its successor EIGRP, which does support VLSM.

IPX, or Internetwork Packet Exchange, is not an IP-based routing protocol at all. It was originally used in older Novell NetWare networks to route IPX traffic, which is part of the IPX/SPX protocol suite. Because IPX operates independently of the IP protocol and does not involve IP addressing, subnetting, or VLSM, it has no relevance to the requirement of supporting VLSM. IPX routing protocols are entirely separate from IP routing technologies and are largely obsolete today.

Since the requirement specifically calls for a classless routing protocol that supports VLSM, OSPF clearly meets this criterion. It offers flexibility, scalability, fast convergence, and efficient IP address usage. Unlike the other protocols mentioned, OSPF fully supports variable subnetting and is therefore the correct choice for modern networks that require classless routing capabilities.

Question 54

Which type of VLAN is used for network management traffic?

A) Management VLAN
B) Native VLAN
C) Data VLAN
D) Voice VLAN

Answer: A) Management VLAN

Explanation

A Management VLAN plays a crucial role in modern network design because it is dedicated solely to handling network management traffic. This includes protocols and tools such as Telnet, SSH, SNMP, and web-based administration interfaces that allow administrators to manage switches, routers, wireless controllers, and other network devices. By assigning a separate VLAN specifically for management tasks, organizations can create a secure and isolated environment that prevents user data, voice streams, or other types of traffic from interfering with or accessing critical management functions. This isolation not only enhances security by limiting who can reach the management plane but also improves performance and reliability, since management packets do not compete with regular data flows for bandwidth. When administrators access devices for configuration, troubleshooting, firmware updates, or monitoring, using a Management VLAN ensures that communication remains stable and protected from unauthorized access or network congestion.

In contrast, the Native VLAN serves a completely different purpose. The Native VLAN on a trunk port is the VLAN that carries untagged traffic. When frames traverse a trunk link between switches or other network devices, most VLANs are tagged to indicate their membership. However, any frame that arrives without a tag is placed into the Native VLAN. This mechanism is primarily used for backward compatibility with devices that may not support tagging. Although the Native VLAN has an important operational function, it is not intended for management tasks and does not provide any specialized protection or isolation for sensitive traffic. Using the Native VLAN for management would expose administrative traffic to unnecessary risks because untagged frames may be mixed with other types of untagged traffic.

The Data VLAN, sometimes referred to as a user VLAN, is the network segment designated for carrying standard user-generated data. This includes tasks such as browsing the internet, accessing shared drives, working with applications, and other everyday network operations. The Data VLAN is designed to support the general communication needs of devices such as computers, printers, and user workstations. Because it carries a wide variety of traffic types and is accessible by many users, it is not suitable for handling network management functions. Placing management traffic in the same VLAN as general data traffic could expose sensitive administrative sessions to potential threats and make it harder to control who can access the management interfaces of critical devices.

Similarly, a Voice VLAN is created specifically to handle voice communication traffic, typically from IP phones. These VLANs are configured to provide Quality of Service features that ensure low latency, minimal jitter, and proper prioritization of voice packets. Voice VLANs help maintain high-quality phone calls by separating voice traffic from data streams that could cause congestion. Since the purpose of a Voice VLAN is to support real-time audio communication, it does not provide any features or isolation intended for management operations. Mixing management traffic with voice traffic would defeat the purpose of maintaining a clean and prioritized communication channel for IP telephony.

Given that the question focuses on which VLAN type is used specifically for network management traffic, the Management VLAN clearly meets the requirement. It is the only VLAN designed to isolate, protect, and support administrative traffic, making it the correct choice.

Question 55

Which command is used to test connectivity to a specific TCP port on a remote device?

A) telnet <IP> <port>
B) ping <IP>
C) traceroute <IP>
D) show ip route

Answer: A) telnet <IP> <port>

Explanation

Using telnet <IP> <port> tests connectivity to a specific TCP port on a remote device. This is useful for troubleshooting service availability, like checking SSH or HTTP access.

Ping only tests ICMP connectivity and does not check specific ports.

Traceroute maps the path packets take but does not test individual port connectivity.

Show ip route displays the routing table and cannot test connectivity.

Because the requirement is testing connectivity to a specific TCP port, telnet <IP> <port> is correct.

Question 56

Which protocol provides secure encrypted remote access to network devices?

A) SSH
B) Telnet
C) HTTP
D) FTP

Answer: A) SSH

Explanation

SSH (Secure Shell) provides encrypted remote access to network devices, ensuring that credentials and data are transmitted securely over insecure networks.

Telnet provides remote access but transmits data in clear text, making it insecure.

HTTP can provide web-based access but is not encrypted unless using HTTPS.

FTP is for file transfers and is also unencrypted in standard form.

Because the question specifies secure encrypted remote access, SSH is correct.

Question 57

Which type of IPv4 address is used for one-to-many communication?

A) Multicast
B) Unicast
C) Broadcast
D) Anycast

Answer: A) Multicast

Explanation

Multicast addressing is a specialized communication method designed to deliver data from one source to multiple selected destinations simultaneously. Instead of sending individual copies of a packet to each recipient, multicast allows a single stream of data to reach all devices that have joined a particular multicast group. This approach significantly reduces bandwidth consumption and minimizes unnecessary traffic on the network. Devices that want to receive multicast traffic must explicitly subscribe to the group, which ensures that only interested hosts process the data. Multicast is commonly used in applications such as streaming media, online conferencing, real-time data feeds, IPTV services, and collaborative tools. By selectively delivering data, multicast enhances efficiency and prevents the overload that would occur if the same information had to be delivered through multiple unicast streams or broad, unsolicited broadcasts.

Unicast communication, in contrast, follows a straightforward one-to-one model. A packet sent using unicast addressing reaches only a single, specific destination device. This method is ideal for situations where direct, personalized communication is required, such as typical web browsing, email exchanges, or file transfers between two devices. While unicast works perfectly for individual communication, it becomes inefficient for distributing the same data to many devices at once. If a server attempted to deliver identical content to multiple recipients using unicast, it would have to generate separate packets for each device, consuming additional bandwidth and processing resources. This inefficiency is precisely why unicast is not suitable for scenarios involving one-to-many communication.

Broadcast communication operates differently by sending packets to all devices within a subnet. When a packet is broadcast, every host on that network segment receives it, regardless of whether it is interested in the information. Broadcast traffic is commonly used for tasks such as ARP requests, DHCP discovery, and other network initialization processes. However, because broadcast traffic reaches every device, it can create unnecessary network load and contribute to congestion, especially in large environments. Additionally, broadcast packets can be disruptive because all devices must process and then discard packets that are irrelevant to them. For these reasons, broadcast communication is not appropriate for targeted one-to-many delivery, as it lacks the precision and efficiency provided by multicast.

Anycast communication is another addressing method, but its purpose is distinct from both multicast and broadcast. In an anycast configuration, multiple devices share the same IP address, and network routing protocols determine which device is the closest or most optimal destination. When a packet is sent to an anycast address, it is delivered to the nearest member of the group based on routing metrics. Anycast is commonly used for services such as DNS, load balancing, and content distribution. It improves performance by minimizing latency and spreading the workload across different servers. However, anycast is fundamentally a one-to-one communication method, even though multiple devices share the address. It does not deliver data to multiple recipients simultaneously, so it does not meet the criteria of one-to-many transmission.

Because the question specifically focuses on one-to-many communication, multicast is the correct choice. It efficiently distributes information to multiple subscribed devices without burdening the entire network or requiring multiple individual streams.

Question 58

Which Layer 2 protocol prevents loops by blocking redundant paths?

A) STP
B) RIP
C) OSPF
D) EIGRP

Answer: A) STP

Explanation

Spanning Tree Protocol, commonly referred to as STP, is an essential mechanism used in Layer 2 network environments to prevent loops from forming when switches are interconnected with redundant links. Redundancy is important for network reliability because it offers backup paths in case a primary link fails. However, without a control mechanism like STP, these redundant connections can create switching loops that cause broadcast storms, duplicate frames, and severe network instability. STP works by identifying redundant paths and selectively blocking some of them, leaving only one active path between any two network segments. Through this process, STP constructs a loop-free logical topology while still preserving physical redundancy for failover purposes. If the active path fails, STP recalculates the topology and unblocks one of the previously disabled links, restoring connectivity while maintaining a loop-free environment.

To perform this function, STP elects a root bridge, calculates the best paths to the root, and determines which ports should be forwarding or blocking. Frames are then forwarded only through the designated forwarding ports. Because Layer 2 switches forward frames based on MAC addresses and have no inherent mechanism to detect loops, STP plays a critical role in ensuring that broadcast, multicast, and even unicast frames do not circulate endlessly throughout the network. Without STP or a similar protocol, a single loop could overwhelm the network within seconds, making it unusable.

By comparison, RIP, which stands for Routing Information Protocol, operates at Layer 3 and is designed for routing decisions in IP networks rather than loop prevention in Layer 2 environments. RIP uses hop count as its metric and shares routing information between routers. While RIP can help route packets between different networks, it has no role in managing the switching topology and cannot prevent Layer 2 loops. It functions entirely differently from STP and is not involved in controlling redundant switch paths.

OSPF, or Open Shortest Path First, is another Layer 3 routing protocol that uses link-state information to compute the shortest path between networks. Like RIP, OSPF deals with routing tables, IP addresses, and network layer topology rather than switch-level loops. Although OSPF ensures efficient and reliable routing between different subnets or autonomous systems, it is not responsible for preventing looping issues that occur in the data-link layer. Its purpose lies in determining optimal paths across a routed infrastructure.

EIGRP, or Enhanced Interior Gateway Routing Protocol, is also a Layer 3 protocol. It combines features of distance-vector and link-state protocols to provide fast convergence and efficient routing. Similar to RIP and OSPF, EIGRP focuses on routing packets between networks and has no mechanism for detecting or preventing switching loops at Layer 2. Its domain is the network layer, and it cannot address the problem of redundant segments in a switched topology.

Since the question specifically concerns the prevention of Layer 2 loops, STP is the correct answer. It uniquely addresses the issue by managing redundancy and ensuring that switch-level communication flows through a loop-free logical path. The other protocols mentioned operate at a different layer of the networking model and therefore do not fulfill the requirement of Layer 2 loop prevention.

Question 59

Which command displays the routing table on a Cisco device?

A) show ip route
B) show mac address-table
C) show arp
D) show interfaces

Answer: A) show ip route

Explanation 

The command show ip route is one of the most important tools used by network administrators to examine and verify a device’s routing table. The routing table contains all known network destinations, including directly connected networks, static routes configured manually by administrators, and dynamically learned routes obtained from routing protocols such as RIP, OSPF, EIGRP, or BGP. When a device receives an IP packet, it consults this routing table to determine the most appropriate path toward the destination network. By using the show ip route command, administrators can confirm whether the device has the correct routes, ensure that routing protocols are functioning properly, and identify any missing or incorrect entries that may be causing connectivity problems. This makes the command essential when diagnosing reachability issues, validating routing configurations, or understanding the overall structure of a network’s forwarding paths.

The information provided by show ip route includes route types, metrics, administrative distances, next-hop addresses, and outgoing interfaces. This level of detail allows administrators to assess how the device makes routing decisions and to verify that traffic is flowing along expected paths. If a network segment becomes unreachable, reviewing the routing table can reveal whether the issue lies in route advertisement, interface status, or misconfiguration. Because routing is fundamental to IP communication, having a clear view of the routing table is critical in maintaining network stability and performance.

In contrast, the command show mac address-table serves a different purpose entirely. Rather than focusing on Layer 3 routing information, it provides insight into Layer 2 switching operations. This command displays the MAC address table of a switch, showing the learned MAC addresses and the specific switch ports associated with those addresses. The MAC address table helps switches forward Ethernet frames efficiently by ensuring they send frames to the correct destination ports rather than flooding them unnecessarily. Although show mac address-table is very useful for diagnosing Layer 2 forwarding issues, VLAN configurations, or endpoint connectivity, it does not provide any information about IP routing or Layer 3 paths.

The show arp command offers another form of network visibility, but again, not related to routing tables. It displays the Address Resolution Protocol cache, which shows mappings between IP addresses and corresponding MAC addresses. This ARP information is essential for devices to deliver packets within the same Layer 2 network segment. Problems such as stale ARP entries, duplicate IP addresses, or incorrect mappings can cause communication failures. While show arp is valuable for troubleshooting certain connectivity issues, it does not reveal routing information or path selection across networks.

The command show interfaces provides details about the operational status and performance statistics of network interfaces. It displays information such as interface state, speed, duplex settings, error counts, and traffic statistics. This helps administrators diagnose physical and data-link layer problems, such as cable issues, collisions, or interface errors. However, despite offering crucial diagnostic data, it does not present routing information or indicate how packets traverse the network.

Because the task specifically involves viewing the routing table and identifying how a device is selecting paths to remote networks, the correct command is show ip route. It is the only one of the options that directly reveals the routing table and allows administrators to analyze and verify routing behavior.

Question 60

Which protocol provides automatic IP address assignment to devices on a network?

A) DHCP
B) ARP
C) ICMP
D) DNS

Answer: A) DHCP

Explanation

Dynamic Host Configuration Protocol, commonly referred to as DHCP, is a network management protocol that simplifies the process of configuring devices on an IP network. DHCP automates the assignment of essential network configuration parameters, including IP addresses, subnet masks, default gateways, and Domain Name System (DNS) server addresses. By automating this process, DHCP eliminates the need for network administrators or users to manually configure each device, which is particularly valuable in large networks where manually assigning addresses to hundreds or thousands of devices would be time-consuming and error-prone. Automatic IP assignment through DHCP also helps prevent address conflicts, which can occur if two devices are inadvertently configured with the same IP address. This reduces administrative overhead and enhances network reliability by ensuring that each device receives a unique and valid network configuration.

When a device connects to a network, it typically sends a DHCP discovery message to locate available DHCP servers. The server responds with an offer that includes an available IP address and other configuration parameters. The device then requests the offered address, and the server confirms the assignment through an acknowledgment. This process, known as the DHCP handshake, allows devices to join the network seamlessly without requiring user intervention. DHCP can also provide lease durations for IP addresses, which ensures that addresses are recycled and reused efficiently, optimizing the utilization of available address space. Additionally, DHCP supports centralized management, which simplifies the administration of network configurations and makes it easier to implement changes, such as updating gateway addresses or DNS server information, across all devices in the network.

Address Resolution Protocol, or ARP, serves a very different purpose. ARP is responsible for mapping IP addresses to the corresponding physical hardware addresses, known as MAC addresses, within a local network. This process is necessary for devices to communicate directly over Ethernet or other Layer 2 networks. While ARP is critical for ensuring that packets reach the correct device on the local network, it does not provide or manage IP address assignments, and therefore cannot replace DHCP in handling automatic configuration.

Internet Control Message Protocol, or ICMP, is primarily used for network diagnostics and error reporting. ICMP messages help identify network issues, report unreachable destinations, and provide feedback about packet delivery problems. Common tools such as ping and traceroute rely on ICMP to test connectivity and measure latency. However, ICMP does not assign IP addresses or configure network settings.

Domain Name System, or DNS, is a service that translates human-readable hostnames into IP addresses, enabling devices to locate servers and services on a network or the internet. While DNS is essential for resolving names to addresses, it does not perform the task of assigning IP addresses to devices. Its function is limited to providing address resolution once the IP address is already configured, either manually or through DHCP.

Because the question specifically focuses on the automatic assignment of IP addresses and other related network settings, DHCP is the correct protocol. It uniquely fulfills the requirement of dynamically configuring devices with the necessary network information while minimizing administrative effort and reducing the risk of configuration errors. No other protocol listed provides this functionality, making DHCP the clear and appropriate choice.