200-301 Cisco Certified Network Associate (CCNA) Exam Dumps and Practice Test Questions Set 3 Q41-60

Visit here for our full Cisco 200-301 exam dumps and practice test questions.

Question 41: 

A network engineer wants to prevent unauthorized devices from connecting to a switch port. Which feature should be configured?

A) DHCP snooping
B) Port security
C) STP
D) EtherChannel

Answer: B

Explanation: 

Port security allows limiting MAC addresses per port and can restrict or shut down the port if unauthorized devices attempt to connect.

To prevent unauthorized devices from connecting to a switch port, a network engineer should configure port security. Port security is a feature on switches that allows administrators to control which devices can access a specific port based on their MAC addresses. By configuring port security, a switch can limit the number of allowed MAC addresses on a port and specify the actions to take when a violation occurs. Actions can include dropping unauthorized traffic, generating alerts, or shutting down the port entirely. This feature is especially useful in environments where physical access to the network is shared or where sensitive data needs to be protected from unauthorized access.

The other options do not directly prevent unauthorized devices from connecting to a port. DHCP snooping is a security feature that filters DHCP messages, helping to prevent rogue DHCP servers from assigning IP addresses on the network. While it protects against DHCP-related attacks, it does not restrict which devices can physically connect to a port. Spanning Tree Protocol (STP) is used to prevent network loops by selectively blocking redundant paths, but it does not enforce port access or security based on connected devices. EtherChannel is a method for combining multiple physical links into a single logical link to increase bandwidth and provide redundancy; it is not a security mechanism and does not control which devices can connect to a port.

Port security works by allowing the administrator to define a set of MAC addresses that are permitted on a given port. These can be configured manually or dynamically learneD) If a device with an unauthorized MAC address attempts to connect, the switch can respond based on the configured violation mode: protect, restrict, or shutdown. The protect mode silently drops the traffic, restrict mode drops the traffic and generates a notification, and shutdown mode places the port in an error-disabled state.

Question 42: 

Which protocol is used to securely manage network devices over an IP network?

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

Answer: C

Explanation: 

SSH (Secure Shell) provides encrypted management access to network devices, while Telnet sends credentials in plaintext and is insecure.

The protocol used to securely manage network devices over an IP network is SSH, or Secure Shell. SSH provides encrypted communication between a client and a network device, such as a router or switch, ensuring that sensitive information like usernames, passwords, and configuration data is protected from eavesdropping or interception. This encryption makes SSH the preferred method for remotely accessing and managing devices compared to older protocols that transmit data in plaintext. By establishing a secure session, administrators can perform configuration changes, monitor device status, and troubleshoot issues without exposing credentials or commands to potential attackers on the network.

Telnet, while also used for remote device management, is an insecure protocol because it sends all data, including login credentials, in plaintext. This means that anyone with access to the network could potentially capture Telnet traffic and gain unauthorized access to network devices. For this reason, Telnet is generally deprecated in modern networks in favor of SSH.

SNMP, or Simple Network Management Protocol, is another protocol related to network device management, but it serves a different purpose. SNMP is primarily used for monitoring and gathering statistics from devices, such as interface traffic, CPU usage, and error rates. While SNMPv3 includes security features like authentication and encryption, SNMP is not typically used for interactive device management or configuration changes in the same way SSH is.

FTP, or File Transfer Protocol, is used to transfer files between hosts on a network. While it can be used to upload or download device configurations, FTP does not provide a secure, interactive management session. FTP transmits data in plaintext, making it vulnerable to interception, and it does not support real-time device configuration like SSH does.

In summary, SSH is the protocol of choice for securely managing network devices because it provides encrypted, interactive access. Telnet and FTP lack encryption, making them insecure, while SNMP focuses on monitoring rather than direct management. SSH ensures that network administrators can safely configure and maintain devices without exposing sensitive information over the network.

Question 43: 

A network engineer needs to allow multiple VLANs over a single physical link between two switches. Which configuration is required?

A) Configure the link as an access port
B) Configure the link as a trunk port using 802.1Q encapsulation
C) Enable STP on the link
D) Assign a static IP to the link

Answer: B

Explanation: 

Trunk ports carry traffic from multiple VLANs by tagging each frame with its VLAN ID using 802.1Q. Access ports carry traffic for a single VLAN only.

When a network engineer needs to allow multiple VLANs to communicate over a single physical link between two switches, the link must be configured as a trunk port using 802.1Q encapsulation. A trunk port is capable of carrying traffic for multiple VLANs by adding a VLAN tag to each Ethernet frame. This tag identifies which VLAN the frame belongs to, allowing the receiving switch to properly segregate and forward the traffic to the correct VLAN. Trunking is essential in larger networks where VLANs are used to segment traffic for security, management, or performance reasons, but physical cabling needs to be minimizeD)

The other options do not achieve this requirement. Configuring the link as an access port limits it to a single VLAN. Access ports are designed to connect end devices like computers or printers to a switch and can only carry untagged traffic associated with a single VLAN. If multiple VLANs need to traverse the same physical connection, using access ports would require separate physical links for each VLAN, which is inefficient and often impractical.

Enabling STP, or Spanning Tree Protocol, on the link is important for loop prevention, but it does not allow multiple VLANs to traverse a single connection. STP helps maintain a loop-free topology and selects the best path in redundant networks, but it does not perform VLAN tagging or trunking functions.

Assigning a static IP to the link is not relevant in this context because VLAN trunking operates at Layer 2. While IP addresses are used for Layer 3 communication, the physical trunk connection is a Layer 2 construct, and IP configuration does not enable multiple VLANs to pass over a single link.

In summary, to allow multiple VLANs over a single physical connection between switches, the link must be configured as a trunk port with 802.1Q encapsulation. Access ports can only carry one VLAN, STP prevents loops but does not handle VLAN tagging, and static IP addressing is unrelated to trunking. Proper trunk configuration ensures that all VLAN traffic is correctly tagged and forwarded across the link, maintaining network segmentation and efficiency.

Question 44: 

Which layer of the OSI model is responsible for logical addressing?

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

Answer: C

Explanation: 

The Network layer (Layer 3) is responsible for logical addressing (IP addresses) and routing packets between networks.

The OSI model organizes network functions into seven layers, each responsible for specific aspects of data communication. Logical addressing is the responsibility of the Network layer, which is Layer 3 of the OSI model. Logical addresses, such as IP addresses, allow devices on different networks to identify each other and communicate effectively. The Network layer uses these addresses to determine the best path for packets to travel from the source device to the destination device across interconnected networks. Routing protocols like OSPF, EIGRP, and BGP operate at this layer to dynamically manage paths and ensure efficient delivery of datA)

The other layers do not handle logical addressing. The Physical layer, which is Layer 1, deals with the transmission of raw bits over physical media such as cables, fiber, or wireless channels. It focuses on electrical signals, light pulses, or radio frequencies, but it does not understand addresses or routing. The Data Link layer, Layer 2, is responsible for physical addressing through MAC addresses, framing, and error detection on a single network segment. While MAC addresses identify devices locally, they are not sufficient for routing across multiple networks, which requires logical addressing. The Transport layer, Layer 4, provides end-to-end communication services for applications, using port numbers to differentiate processes on the same host. Although the Transport layer ensures data delivery and error checking, it does not determine how packets are routed or identify devices on a network.

By providing logical addressing, the Network layer enables scalable and hierarchical addressing schemes, allowing networks to grow without address conflicts. IP addressing, subnetting, and routing decisions are all functions of this layer, making it fundamental for inter-network communication.

Question 45: 

Which command shows the OSPF routing table on a Cisco router?

A) show ip route ospf
B) show ip ospf database
C) show running-config
D) show ip interface brief

Answer: A

Explanation: 

show ip route ospf displays routes learned via OSPF in the routing table, including prefixes, next hops, and outgoing interfaces.

The command used to display the OSPF routing table on a Cisco router is show ip route ospf. This command provides a detailed view of all routes that have been learned through the OSPF protocol, including the network prefixes, the next-hop IP addresses, and the outgoing interfaces used to reach each destination. By using this command, network administrators can verify that OSPF routes are being properly received, installed in the routing table, and used for forwarding traffiC) It is especially useful for troubleshooting routing issues, confirming network connectivity, and validating OSPF configurations.

The other commands do not provide the same information. The show ip ospf database command displays the contents of the OSPF link-state database, including all Link-State Advertisements (LSAs) received from neighboring routers. While this command helps in understanding the OSPF topology and how routers are exchanging information, it does not show which routes have actually been installed in the routing table for packet forwarding.

The show running-config command displays the current configuration of the router, including OSPF process configuration, network statements, and interface settings. Although it provides insight into how OSPF is configured, it does not indicate which routes are actively being used or which next-hop paths have been selecteD)

The show ip interface brief command provides a summary of the router’s interfaces, including their IP addresses, status, and protocol state. This command is useful for verifying interface connectivity and operational status but does not provide any information about routing protocols or learned routes.

In summary, show ip route ospf is the command specifically designed to display the routes that OSPF has learned and installed in the routing table. It provides essential information such as the destination networks, the next-hop IP addresses, and the outgoing interfaces, which are crucial for network troubleshooting and verification. The other commands, while useful for configuration and status information, do not provide a direct view of the active OSPF routing table.

Question 46: 

Which IPv4 address is reserved for loopback testing?

A) 0.0.0.0
B) 127.0.0.1
C) 169.254.0.1
D) 255.255.255.255

Answer: B

Explanation: 

127.0.0.1 is the IPv4 loopback address used to test TCP/IP stack functionality on the local device.

The IPv4 address reserved for loopback testing is 127.0.0.1. This address allows a device to send network traffic to itself, effectively testing the functionality of the TCP/IP stack without requiring a physical network connection. When a packet is sent to 127.0.0.1, it never leaves the host; instead, it is looped back internally to the sending device. This makes the loopback address an essential tool for diagnosing and troubleshooting network stack issues, verifying that the IP software is correctly installed, and ensuring that applications relying on TCP/IP can function properly.

The other addresses listed serve different purposes. The address 0.0.0.0 is a non-routable meta-address used to indicate an unknown or default network. For example, it can represent a default route in routing tables or denote that a device has not yet been assigned an IP address. It is not used for testing the local TCP/IP stack.

169.254.0.1 falls within the Automatic Private IP Addressing (APIPA) range, which spans 169.254.0.0 to 169.254.255.255. APIPA addresses are automatically assigned to hosts when a DHCP server cannot be reacheD) While this allows limited local connectivity between devices on the same subnet, it is unrelated to loopback testing and does not verify the integrity of the local TCP/IP stack.

255.255.255.255 is the limited broadcast address used to send a message to all hosts on a local network segment. This address is used in scenarios such as DHCP discovery when a device does not yet have an IP address, but it is not intended for testing the device itself.

In summary, 127.0.0.1 is the reserved IPv4 loopback address used to test the TCP/IP functionality on the local device. Other addresses such as 0.0.0.0, 169.254.0.1, and 255.255.255.255 have specific purposes in routing, automatic addressing, or broadcasting, but they do not serve as loopback addresses for local testing. Using 127.0.0.1 ensures that administrators and applications can confirm that the network stack is operational without sending traffic over the physical network.

Question 47: 

Which protocol dynamically assigns IP addresses to hosts?

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

Answer: C

Explanation: 

DHCP assigns IP addresses, subnet masks, default gateways, and DNS server information automatically to hosts, reducing manual configuration errors.

The protocol that dynamically assigns IP addresses to hosts is DHCP, or Dynamic Host Configuration Protocol. DHCP allows network devices to automatically obtain IP configuration information, including an IP address, subnet mask, default gateway, and DNS server addresses, without requiring manual configuration. This automation reduces the potential for configuration errors and makes managing large networks more efficient. When a host connects to a network, it sends a DHCP discovery message, and the DHCP server responds with an offer of available IP configuration. The host then requests the offered address, and the server acknowledges it, completing the lease process. DHCP leases can be temporary, allowing efficient reuse of IP addresses within a network.

The other protocols listed serve different purposes. ARP, or Address Resolution Protocol, is used to map a known IP address to a corresponding MAC address on a local network. ARP is essential for communication within a subnet but does not assign IP addresses dynamically. DNS, or Domain Name System, translates human-readable domain names into IP addresses so that devices can locate servers or other hosts on a network. While DNS relies on IP addresses to function, it does not assign them to hosts. ICMP, or Internet Control Message Protocol, is used for network diagnostics and error reporting, such as indicating that a host is unreachable or performing tests with tools like ping. ICMP does not provide any IP addressing services.

DHCP streamlines network management, particularly in environments with many hosts, by eliminating the need for manual IP assignment. It also supports centralized control of IP addressing, helping administrators prevent conflicts caused by duplicate addresses. DHCP can provide additional network configuration information, such as default gateways, DNS servers, and other options, ensuring that hosts can communicate effectively without manual intervention.

In summary, DHCP is the protocol responsible for dynamically assigning IP addresses and other network configuration details to hosts. ARP, DNS, and ICMP perform vital network functions, such as address resolution, name resolution, and diagnostics, but they do not provide dynamic IP assignment.

Question 48: 

In RIP, which metric is used to determine the best path?

A) Bandwidth
B) Delay
C) Hop count
D) Cost

Answer: C

Explanation: 

RIP uses hop count as its sole metric, with a maximum of 15 hops. Paths with a hop count of 16 are considered unreachable.

In the Routing Information Protocol (RIP), the metric used to determine the best path to a destination network is hop count. Hop count represents the number of routers a packet must pass through to reach its destination. When multiple paths exist to a network, RIP selects the path with the lowest hop count as the preferred route. This simplicity makes RIP easy to configure and understand but also limits its scalability in larger networks. RIP defines a maximum hop count of 15, meaning any network more than 15 hops away is considered unreachable, which prevents routing loops but restricts its use in extensive or complex topologies.

Other metrics used by different routing protocols are not applicable in RIP. Bandwidth is used by protocols such as EIGRP to calculate the best path based on link speed, favoring higher-capacity links. Delay, also considered by EIGRP, accounts for the time it takes for a packet to traverse a link. Cost is the metric used by OSPF, calculated based on link speed, where lower-cost links are preferred for routing decisions. While these metrics provide more granular and efficient path selection, RIP relies solely on hop count, which can lead to suboptimal routing in networks where links have varying speeds or delays.

Because RIP only counts hops, it does not differentiate between fast or slow links. For example, a path through three low-bandwidth routers may be chosen over a path through four high-speed routers simply because its hop count is lower. This limitation can result in inefficient routing in modern networks, which is why RIP is generally used in smaller or simpler environments rather than large enterprise networks.

Question 49: 

A network engineer wants to prevent loops in a Layer 2 network with redundant links. Which protocol should be used?

A) OSPF
B) RIP
C) STP
D) BGP
Answer: C

Explanation: 

Spanning Tree Protocol prevents Layer 2 loops by placing redundant links into a blocked state while maintaining at least one active path.

To prevent loops in a Layer 2 network with redundant links, the Spanning Tree Protocol (STP) should be useD) STP is specifically designed for Ethernet networks to maintain a loop-free topology. In Layer 2 networks, redundant links are often deployed to provide backup paths in case of link or switch failures. However, multiple active paths can create switching loops, leading to broadcast storms, multiple frame copies, and MAC table instability. STP addresses this issue by logically blocking certain redundant paths while keeping at least one active path for traffic forwarding. If an active link fails, STP automatically recalculates the topology and activates one of the previously blocked links, ensuring continued network availability.

The other options are not suitable for preventing Layer 2 loops. OSPF is a Layer 3 routing protocol used to determine the best path between networks based on cost. While it prevents routing loops at Layer 3, it does not operate at Layer 2 and cannot block redundant Ethernet links. RIP is another Layer 3 routing protocol that uses hop count as a metric to determine the best path for IP traffiC) Like OSPF, RIP addresses routing loops between networks but has no effect on Layer 2 loops caused by multiple active switches. BGP is a path-vector protocol used primarily in inter-domain routing for exchanging routing information between autonomous systems on the Internet. It operates at Layer 3 and does not interact with Layer 2 switching loops.

STP works by electing a root bridge and calculating the shortest path from all switches to the root. Ports not on the shortest path are placed in a blocking state, preventing loops while maintaining redundancy. Variations of STP, such as Rapid Spanning Tree Protocol (RSTP), improve convergence time, allowing blocked links to quickly transition to forwarding in case of a failure.

In summary, STP is the essential protocol for preventing loops in Layer 2 networks with redundant links. OSPF, RIP, and BGP operate at Layer 3 and focus on routing IP packets, making them unsuitable for solving switching loops at the data link layer. STP ensures loop-free topologies while maintaining fault tolerance and redundancy.

Question 50: 

Which IPv6 feature provides automatic address configuration without a DHCP server?

A) SLAAC (Stateless Address Autoconfiguration)
B) NAT
C) ARP
D) Anycast

Answer: A

Explanation: 

SLAAC allows IPv6 devices to generate their own addresses using the network prefix advertised by routers without needing a DHCP server.

The IPv6 feature that provides automatic address configuration without requiring a DHCP server is SLAAC, or Stateless Address Autoconfiguration. SLAAC allows devices to generate their own IPv6 addresses using the network prefix advertised by local routers through Router Advertisement (RA) messages. When a device connects to a network, it listens for these RA messages and combines the advertised prefix with its own interface identifier, often derived from its MAC address, to create a globally unique IPv6 address. This process eliminates the need for manual IP configuration or a DHCP server, simplifying network management and enabling plug-and-play connectivity for IPv6-enabled devices.

The other options listed serve different purposes in networking. NAT, or Network Address Translation, is used primarily in IPv4 networks to map private IP addresses to a public IP address for communication over the Internet. NAT is not an address configuration mechanism and is generally not used in IPv6, as the large address space reduces the need for address translation. ARP, or Address Resolution Protocol, is used in IPv4 to map IP addresses to MAC addresses within a local network. IPv6 replaces ARP with Neighbor Discovery Protocol (NDP), and ARP does not provide automatic IP address assignment. Anycast is an addressing method where multiple devices share the same IP address, and traffic is routed to the nearest device in terms of routing distance. While useful for redundancy and load balancing, anycast does not configure addresses automatically for hosts.

SLAAC also allows devices to configure additional parameters such as default gateways and network prefixes, providing basic connectivity without the intervention of a DHCPv6 server. However, in networks that require more detailed configuration, DHCPv6 can still be used alongside SLAAC to provide options like DNS server addresses.

Question 51: 

Which command verifies which VLAN a switch port is assigned to?

A) show vlan brief
B) show mac-address-table
C) show interfaces status
D) show running-config

Answer: C

Explanation: 

show interfaces status shows the operational VLAN for each switch port, along with duplex, speed, and port status.

The command used to verify which VLAN a switch port is assigned to is show interfaces status. This command provides a summary of all switch ports, showing key details such as the port’s operational VLAN, duplex mode, speed, and status (up or down). By using this command, a network administrator can quickly determine which VLAN each interface belongs to, helping to troubleshoot connectivity issues, verify configuration, and ensure that devices are correctly segmented according to the network design. The operational VLAN displayed reflects the VLAN currently in use on the port, which is particularly useful when working with access ports that carry a single VLAN.

The other commands provide related but different information. The show vlan brief command displays all VLANs configured on the switch, their names, status (active or suspended), and the ports that are assigned to each VLAN. While it provides an overview of VLAN configuration, it may not always reflect the current operational status of a specific port. The show mac-address-table command displays the MAC addresses learned on each port and the associated VLAN. While it can be used indirectly to infer VLAN assignments by examining where MAC addresses are learned, it is primarily for checking device connectivity rather than confirming port VLAN assignment. The show running-config command shows the current configuration of the switch, including interface VLAN assignments. While it reflects the intended configuration, it may not show the actual operational VLAN if there is a mismatch or if the port is administratively down.

By using show interfaces status, administrators can quickly identify both the configured and operational VLAN of each interface in a single view. This command is especially valuable when verifying access ports, troubleshooting VLAN-related connectivity issues, or confirming that switch ports are active and properly configureD) It provides immediate, practical information for managing VLANs and ensuring network segmentation is functioning as intendeD)

In summary, show interfaces status is the most direct and effective command to verify the VLAN assignment of a switch port, while show vlan brief, show mac-address-table, and show running-config provide complementary information but do not give the operational VLAN for each port as clearly.

Question 52: 

Which type of NAT assigns the same public IP to a single private IP?

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

Answer: A

Explanation: 

Static NAT maps one private IP to one public IP permanently, often used for servers that require a fixed public address.

The type of NAT that assigns the same public IP address to a single private IP address is Static NAT. Static NAT provides a one-to-one mapping between a private IP and a public IP, meaning that the private host always uses the same public IP when communicating with external networks. This is particularly useful for devices such as web servers, email servers, or VPN endpoints that need a consistent public address to be reachable from the internet. By maintaining a permanent mapping, Static NAT ensures predictable communication and simplifies firewall and routing configurations.

Other types of NAT function differently. Dynamic NAT maps a private IP to a public IP from a pool of available addresses. Unlike Static NAT, the mapping is temporary and assigned only when the host initiates a connection. Once the connection ends, the public IP may be reassigned to another private host. Dynamic NAT is useful when multiple devices need internet access, but none require a fixed public IP, allowing efficient use of limited public addresses.

PAT, also known as NAT overload, allows multiple private IP addresses to share a single public IP by differentiating connections using port numbers. This type of NAT is widely used in home and small business networks where many devices access the internet through one public IP. While efficient for address conservation, PAT does not provide a one-to-one mapping, making it unsuitable for servers or devices that must be consistently reachable.

Static NAT is configured manually, defining both the private and public IP addresses in the router or firewall. Once configured, the mapping remains constant, providing reliability for external clients trying to reach a specific host. This permanence distinguishes Static NAT from Dynamic NAT and PAT, which assign public addresses temporarily or share them among multiple hosts.

In summary, Static NAT assigns the same public IP to a single private IP permanently, ensuring consistent accessibility for services requiring a fixed external address. Dynamic NAT assigns temporary public addresses from a pool, while PAT allows multiple hosts to share a single public IP using port numbers, making them unsuitable for devices that need a permanent public presence.

Question 53: 

Which IPv6 address is used to communicate with all routers on a local link?

A) FF02::1
B) FF02::2
C) FE80::1
D) FF00::1

Answer: B

Explanation: 

FF02::2 is the all-routers multicast address, used to reach all routers on the same link.

In IPv6, the address used to communicate with all routers on a local link is FF02::2. This is a link-local multicast address specifically reserved for reaching every router on the same subnet. When a packet is sent to FF02::2, all routers on the local link will receive it, making it useful for tasks such as router discovery, routing protocol updates, or network management operations that need to reach all routers without sending traffic individually to each device. Because it is a multicast address, only routers configured to listen to this group respond, ensuring efficient communication without unnecessary traffic to non-router devices.

Other IPv6 addresses listed serve different purposes. FF02::1 is the all-nodes multicast address, which targets all IPv6-enabled devices on the local link, including both hosts and routers. While it allows messages to reach every node, it is broader than FF02::2, which specifically targets routers only. FE80::1 falls within the link-local unicast range (FE80::/10) and represents a single host on the local link. Link-local unicast addresses are used for communication between individual devices on the same subnet, not for multicast communication with all routers. FF00::1 is not a standard IPv6 multicast address; FF00::/8 is the general prefix for IPv6 multicast addresses, and the remaining bits define specific groups and scopes. FF00::1 does not correspond to the all-routers group and would not serve the same purpose as FF02::2.

Using FF02::2 ensures that messages intended for routers on a link are efficiently delivered without impacting other devices. This is particularly important for protocols such as OSPFv3, EIGRP for IPv6, or ICMPv6-based router discovery, where routers need to exchange information regularly to maintain proper routing tables.

Question 54: 

Which command is used to verify a switch’s MAC address table?

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

Answer: B

Explanation: 

show mac-address-table displays all MAC addresses learned by the switch and the corresponding ports, aiding in troubleshooting connectivity issues.

The command used to verify a switch’s MAC address table is show mac-address-table. This command provides a detailed view of all the MAC addresses that a switch has learned on its ports, along with the associated VLAN and the interface through which each MAC address was learneD) By using this command, network administrators can identify which devices are connected to specific ports, verify proper VLAN assignments, and troubleshoot connectivity issues. It is particularly useful in resolving problems such as port misconfigurations, unexpected network traffic, or identifying unknown devices on the network.

Other commands listed serve different purposes. The show ip route command displays the router’s or Layer 3 switch’s routing table, showing the available network routes, next-hop addresses, and interface information. While useful for troubleshooting routing and Layer 3 connectivity, it does not provide information about MAC addresses or Layer 2 connectivity. The show running-config command displays the current configuration of the switch, including VLAN configurations, interface settings, and security features. Although it shows how the switch is configured, it does not indicate which MAC addresses have actually been learned on the ports. The show arp command displays the Address Resolution Protocol table, mapping IP addresses to MAC addresses. While this can help verify Layer 3 to Layer 2 address resolution, it is limited to IP-to-MAC mappings and does not show all MAC addresses that the switch has learned for traffic forwarding purposes.

The MAC address table is fundamental for switch operation because switches use it to forward frames to the correct destination port. Without an accurate MAC address table, frames might be flooded unnecessarily to all ports, leading to network inefficiency and potential congestion. The show mac-address-table command allows administrators to monitor this table in real-time and confirm that the switch is learning and maintaining MAC addresses correctly.

In summary, show mac-address-table is the command that provides a comprehensive view of all MAC addresses learned by a switch and their associated ports, aiding in Layer 2 troubleshooting and network verification. Commands like show ip route, show running-config, and show arp provide related but distinct information and do not directly display the switch’s MAC address table.

Question 55: 

A router receives a packet destined for an unknown network and has a default route configureD) What happens?

A) The packet is dropped
B) The packet is forwarded to the next-hop defined by the default route
C) An ICMP unreachable message is sent
D) The packet is broadcasted

Answer: B

Explanation: 

A default route is used to forward packets to a predefined next-hop when the destination network is unknown.

When a router receives a packet destined for a network that is not present in its routing table, it will refer to the default route if one is configureD) A default route acts as a catch-all path for any packets whose destination networks are unknown to the router. The router forwards the packet to the next-hop IP address or outgoing interface specified in the default route. This mechanism ensures that traffic can still reach external networks or the internet even if the router does not have specific route entries for every possible network. The default route is often configured as 0.0.0.0/0 in IPv4 or ::/0 in IPv6, representing all networks not explicitly listed in the routing table.

If a default route were not configured, the router would have to drop packets destined for unknown networks, as it would have no knowledge of where to send them. This behavior is captured by option A, but with a default route present, packet dropping does not occur. Option C, sending an ICMP unreachable message, typically happens when a router receives a packet with no matching route and no default route is available, notifying the source that the destination is unreachable. This is part of standard error reporting in IP networks but does not apply when a default route exists. Option D, broadcasting the packet, is not correct because routers do not broadcast unknown packets to all interfaces; forwarding decisions are made based on routing information, and broadcasting at Layer 3 is generally limited to specific scenarios like ARP or certain service discovery protocols.

Question 56: 

Which feature allows a switch to prevent rogue DHCP servers from assigning IP addresses?

A) DHCP snooping
B) Port security
C) ARP inspection
D) Access Control List

Answer: A

Explanation: 

DHCP snooping identifies trusted and untrusted ports and blocks DHCP responses from unauthorized servers, protecting hosts from incorrect IP assignments.The feature that allows a switch to prevent rogue DHCP servers from assigning IP addresses is DHCP snooping. DHCP snooping acts as a security mechanism on switches to protect the network from unauthorized or rogue DHCP servers that could provide incorrect IP configuration to clients. When DHCP snooping is enabled, the switch differentiates between trusted and untrusted ports. Trusted ports are typically uplinks to legitimate DHCP servers or other network infrastructure, while untrusted ports are connected to end devices such as computers or printers. DHCP responses coming from untrusted ports are blocked, ensuring that only authorized servers can assign IP addresses. This helps prevent network issues such as IP conflicts, misrouting, or attacks that rely on giving clients incorrect gateway or DNS information.

Other options in the question perform different security functions but do not directly prevent rogue DHCP servers. Port security limits access to a switch port based on MAC addresses, controlling which devices can connect to the network. While port security can prevent unauthorized devices from connecting, it does not regulate DHCP responses or prevent a rogue DHCP server from sending IP assignments. ARP inspection, specifically Dynamic ARP Inspection (DAI), protects against ARP spoofing by validating ARP requests and responses, ensuring they match known IP-to-MAC bindings. This helps prevent man-in-the-middle attacks but does not control DHCP server activity. Access Control Lists (ACLs) can filter traffic based on IP addresses, protocols, or ports, providing general network access control. However, ACLs do not automatically identify and block rogue DHCP responses, making them insufficient for this specific function.

Question 57: 

A network engineer is troubleshooting OSPF. Which interface parameter must match on two OSPF neighbors?

A) IP address
B) Hello and dead timers
C) Subnet mask
D) MAC address

Answer: B

Explanation: 

Hello and dead timers must match between OSPF neighbors; mismatched timers prevent adjacency formation.

Question 58: 

Which Layer 2 protocol is responsible for resolving IP addresses to MAC addresses?

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

Answer: B

Explanation: 

ARP (Address Resolution Protocol) resolves IPv4 addresses to MAC addresses, allowing frames to be delivered within a local network segment.

Question 59: 

A switch is configured with EtherChannel. What is the primary benefit?

A) Increased security
B) Redundant links without STP blocking
C) Load balancing and increased bandwidth
D) VLAN segmentation

Answer: C

Explanation: 

EtherChannel combines multiple physical links into a single logical link, providing load balancing, redundancy, and higher throughput.

When a switch is configured with EtherChannel, the primary benefit is load balancing and increased bandwidth. EtherChannel allows multiple physical links between switches or between a switch and a server to be bundled into a single logical link. This logical aggregation enables traffic to be distributed across all member links, effectively increasing the total available bandwidth between devices. For example, combining four 1 Gbps links into an EtherChannel results in an aggregated bandwidth of 4 Gbps. In addition to higher throughput, EtherChannel provides redundancy: if one of the physical links in the bundle fails, traffic continues to flow over the remaining active links, minimizing network disruption.

Other options listed are either secondary benefits or unrelateD) Increased security is not a direct benefit of EtherChannel. While EtherChannel can be configured alongside security features, its main purpose is not to provide protection against attacks. Redundant links without STP blocking is partially true in that EtherChannel reduces the need for Spanning Tree Protocol to block redundant links individually. However, STP still views the EtherChannel as a single logical link, and blocking is avoided because multiple links are bundled, not because STP itself is disableD) EtherChannel achieves redundancy through link aggregation, but its primary focus is on bandwidth utilization rather than purely redundancy. VLAN segmentation, option D, is unrelateD) VLANs define broadcast domains and traffic separation on a switch, whereas EtherChannel deals with combining multiple physical links to act as a single logical channel; it does not inherently segment VLANs.

EtherChannel can be configured using protocols such as PAgP (Port Aggregation Protocol) or LACP (Link Aggregation Control Protocol), which help manage link negotiation and ensure all member links are compatible. By using EtherChannel, network designers can optimize performance, increase link resilience, and simplify management by treating multiple physical connections as a single logical interface.

In summary, the primary benefit of EtherChannel is load balancing and increased bandwidth through aggregation of multiple links. Redundancy is a secondary benefit, while increased security and VLAN segmentation are unrelated to EtherChannel’s main purpose.

Question 60: 

Which command displays a router’s running configuration, including all interface and protocol settings?

A) show ip route
B) show running-config
C) show startup-config
D) show interfaces

Answer: B

Explanation: 

show running-config displays the current active configuration in RAM, including interface IPs, routing protocols, passwords, and VLAN settings.