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Question 321. Which Cisco IOS command displays detailed information about the interfaces on a device?

1. show version
2. show ip route
3. show vlan brief
4. show interfaces

Correct Answer: 4. show interfaces

Explanation :-

The show interfaces command displays detailed information about interfaces on a Cisco device. Depending on the interface, the output can include administrative and operational status, bandwidth, duplex and speed settings, packet counters, errors, collisions, encapsulation, and other statistics. This makes the command valuable when troubleshooting physical and data-link connectivity problems. show version provides system information, show ip route displays the routing table, and show vlan brief summarizes VLAN configuration. Therefore, show interfaces is the appropriate command when detailed interface information is required.

Question 322. Which IPv4 address is a valid private address?

1. 10.45.20.15
2. 11.45.20.15
3. 172.32.10.5
4. 192.169.1.5

Correct Answer: 1. 10.45.20.15

Explanation :-

The IPv4 address 10.45.20.15 belongs to the private 10.0.0.0/8 address range defined by RFC 1918. Private IPv4 addresses are commonly used inside organizations and are not directly routable across the public Internet. The other private ranges are 172.16.0.0/12 and 192.168.0.0/16. The address 172.32.10.5 is outside the private 172.16.0.0/12 range, while 192.169.1.5 is outside the private 192.168.0.0/16 range. Therefore, 10.45.20.15 is the valid private IPv4 address.

Question 323. Which protocol is used to resolve an IPv4 address into a MAC address on an Ethernet network?

1. DNS
2. DHCP
3. ARP
4. NTP

Correct Answer: 3. ARP

Explanation :-

Address Resolution Protocol (ARP) resolves an IPv4 address to the corresponding MAC address on a local Ethernet network. When a host knows the destination IPv4 address but needs the Layer 2 address required to construct an Ethernet frame, it can use an ARP request. The device that owns the IPv4 address responds with its MAC address, and the mapping can then be stored in the ARP cache. DNS resolves names to IP addresses, DHCP provides network configuration, and NTP synchronizes clocks. Therefore, ARP is the protocol responsible for IPv4-to-MAC address resolution.

Question 324. Which subnet mask corresponds to an IPv4 /27 prefix?

1. 255.255.255.192
2. 255.255.255.224
3. 255.255.255.240
4. 255.255.255.128

Correct Answer: 2. 255.255.255.224

Explanation :-

A /27 IPv4 prefix contains 27 network bits and 5 host bits. The first three octets are completely dedicated to the network portion, while the fourth octet contains three network bits. Three network bits produce the decimal value 224 in the final octet, giving the subnet mask 255.255.255.224. A /26 uses 255.255.255.192, /28 uses 255.255.255.240, and /25 uses 255.255.255.128. Therefore, 255.255.255.224 is the correct subnet mask for a /27 prefix.

Question 325. Which routing protocol uses cost as its primary metric and is classified as a link-state protocol?

1. RIP
2. FTP
3. ARP
4. OSPF

Correct Answer: 4. OSPF

Explanation :-

Open Shortest Path First (OSPF) is a link-state interior gateway routing protocol that uses a cost metric to select routes. OSPF routers exchange link-state information and construct a topology database, then use the Shortest Path First algorithm to calculate paths. OSPF cost is commonly influenced by interface bandwidth. RIP uses hop count as its metric, while FTP is a file-transfer protocol and ARP resolves IPv4 addresses to MAC addresses. OSPF supports hierarchical designs using areas and is widely used in enterprise networks. Therefore, OSPF is the correct routing protocol described.

Question 326. What is the primary purpose of a default route?

1. To provide a path when no more specific route matches a destination
2. To assign MAC addresses to hosts
3. To prevent Layer 2 loops
4. To identify the local VLAN

Correct Answer: 1. To provide a path when no more specific route matches a destination

Explanation :-

A default route provides a forwarding path for destinations that do not match a more specific entry in the routing table. In IPv4, the default route is commonly represented as 0.0.0.0/0. It is often configured on routers that forward unknown external destinations toward an upstream provider or another gateway. A default route does not assign MAC addresses, prevent Layer 2 loops, or identify VLAN membership. Routers first look for the most specific matching route, and the default route can be used when no more specific match exists. Therefore, providing a fallback forwarding path is the primary purpose of a default route.

Question 327. Which command displays the IPv6 addresses configured on a specific Cisco interface?

1. show ip route
2. show arp
3. show ipv6 interface
4. show vlan brief

Correct Answer: 3. show ipv6 interface

Explanation :-

The show ipv6 interface command displays detailed IPv6 information for a specified interface. The output can include configured IPv6 addresses, link-local addresses, operational status, IPv6 enablement, and other IPv6-related information. This command is useful for troubleshooting IPv6 configuration and verifying that expected addresses are present. show ip route displays the IPv4 routing table, show arp displays IPv4 ARP information, and show vlan brief summarizes VLANs. Therefore, show ipv6 interface is the appropriate command for detailed IPv6 interface information.

Question 328. Which Layer 2 technology allows VLAN information to be carried across a trunk link?

1. NAT
2. 802.1Q
3. ARP
4. ICMP

Correct Answer: 2. 802.1Q

Explanation :-

IEEE 802.1Q is the standard VLAN trunking technology used to identify VLAN membership as Ethernet frames travel across a trunk link. It inserts a VLAN tag into Ethernet frames so that multiple VLANs can share the same physical connection while remaining logically separated. Trunk links are commonly used between switches or between switches and Layer 3 devices configured for inter-VLAN routing. NAT translates IP addresses, ARP resolves IPv4 addresses to MAC addresses, and ICMP provides control and diagnostic messaging. Therefore, 802.1Q is the Layer 2 technology associated with VLAN tagging on trunk links.

Question 329. Which Cisco command displays directly connected Cisco devices discovered using CDP?

1. show cdp neighbors
2. show ip route
3. show startup-config
4. show interfaces

Correct Answer: 1. show cdp neighbors

Explanation :-

The show cdp neighbors command displays information about directly connected Cisco devices discovered through Cisco Discovery Protocol. The output can include the neighboring device’s hostname, platform, capabilities, local interface, and remote interface. This information is useful for understanding physical topology and troubleshooting connections between Cisco devices. show ip route displays routing information, show startup-config displays the saved configuration, and show interfaces provides detailed interface statistics. Therefore, show cdp neighbors is the correct command for viewing directly connected Cisco neighbors.

Question 330. Which protocol provides reliable, connection-oriented transport for applications?

1. UDP
2. TCP
3. ARP
4. ICMP

Correct Answer: 2. TCP

Explanation :-

Transmission Control Protocol (TCP) provides reliable, connection-oriented transport between applications. TCP establishes a connection before transferring application data and uses sequence numbers, acknowledgments, retransmissions, and flow-control mechanisms to support reliable delivery. UDP is connectionless and does not provide TCP’s built-in reliability mechanisms. ARP is used for IPv4 address resolution on local networks, while ICMP is used for control and diagnostic messaging. Applications such as SSH and many HTTP-based services commonly use TCP. Therefore, TCP is the transport-layer protocol that provides reliable, connection-oriented communication.

Question 331. Which IPv6 address is the loopback address?

1. FE80::1
2. FF02::1
3. 2001:DB8::1
4. ::1

Correct Answer: 4. ::1

Explanation :-

The IPv6 address ::1 is the loopback address. It identifies the local host and is used to test the local IPv6 protocol stack without sending packets onto the physical network. It serves a purpose similar to IPv4 address 127.0.0.1. FE80::/10 represents link-local unicast addresses, FF02::1 is a multicast address used for all IPv6 nodes on the local link, and 2001:DB8::/32 is reserved for documentation. Therefore, ::1 is the correct IPv6 loopback address.

Question 332. Which Cisco feature can combine several physical Ethernet interfaces into one logical interface?

1. DHCP snooping
2. Port security
3. EtherChannel
4. NTP

Correct Answer: 3. EtherChannel

Explanation :-

EtherChannel combines multiple physical Ethernet links into a single logical link. This provides increased aggregate bandwidth and redundancy while allowing the bundled interfaces to be managed as one logical connection. EtherChannel can be negotiated using protocols such as LACP or PAgP, depending on device capabilities and configuration. DHCP snooping protects against unauthorized DHCP servers, port security restricts MAC addresses on ports, and NTP synchronizes clocks. EtherChannel is commonly used between switches and other devices that support link aggregation. Therefore, EtherChannel is the correct feature for combining physical Ethernet interfaces.

Question 333. Which command displays the VLAN membership and status of switch ports?

1. show vlan brief
2. show ip route
3. show arp
4. show version

Correct Answer: 1. show vlan brief

Explanation :-

The show vlan brief command displays VLAN information including VLAN IDs, names, status, and access ports assigned to each VLAN. It is commonly used to verify VLAN configuration and determine whether access interfaces belong to the expected VLAN. The command provides a concise view that is useful during troubleshooting. show ip route displays routing information, show arp displays IPv4-to-MAC mappings, and show version provides system and software information. Therefore, show vlan brief is the appropriate command for checking VLAN membership and status on a Cisco switch.

Question 334. Which IPv4 address represents the limited broadcast address?

1. 0.0.0.0
2. 127.0.0.1
3. 224.0.0.1
4. 255.255.255.255

Correct Answer: 4. 255.255.255.255

Explanation :-

The IPv4 address 255.255.255.255 is the limited broadcast address. A packet sent to this address is intended for all IPv4 hosts on the local network segment and is not forwarded by routers. 0.0.0.0 is used in several special contexts, including representing an unspecified address or default route depending on the context. 127.0.0.1 is the IPv4 loopback address, while 224.0.0.1 is an IPv4 multicast address used for all hosts on the local subnet. Therefore, 255.255.255.255 is the correct limited broadcast address.

Question 335. Which command displays the saved configuration that will normally be loaded when a Cisco device starts?

1. show startup-config
2. show running-config
3. show interfaces
4. show version

Correct Answer: 1. show startup-config

Explanation :-

The show startup-config command displays the configuration saved in NVRAM and normally used during device startup. Administrators use this command to verify whether configuration changes have been saved. The running configuration is stored in RAM and may differ from the startup configuration if recent changes have not been copied to NVRAM. show running-config displays the active configuration, show interfaces provides interface information, and show version provides system details. Therefore, show startup-config is the correct command for viewing the saved startup configuration.

Question 336. Which security feature can prevent unauthorized devices from obtaining IP addresses from a rogue DHCP server?

1. NAT
2. DHCP snooping
3. EtherChannel
4. CDP

Correct Answer: 2. DHCP snooping

Explanation :-

DHCP snooping is a switch security feature that helps protect against rogue DHCP servers. It classifies switch interfaces as trusted or untrusted and can prevent unauthorized DHCP server responses from reaching clients through untrusted interfaces. DHCP snooping can also create a binding database containing client information such as MAC addresses, IP addresses, VLANs, and ports. NAT performs address translation, EtherChannel aggregates links, and CDP discovers Cisco neighbors. Therefore, DHCP snooping is the feature designed to help prevent unauthorized DHCP server activity on a switched network.

Question 337. Which protocol is used to synchronize time across network devices?

1. NTP
2. FTP
3. ARP
4. STP

Correct Answer: 1. NTP

Explanation :-

Network Time Protocol (NTP) is used to synchronize clocks across network devices. Accurate time synchronization helps administrators correlate events in logs, troubleshoot incidents, support authentication mechanisms, and maintain consistent timestamps throughout an infrastructure. NTP commonly communicates using UDP port 123. FTP provides file transfer, ARP resolves IPv4 addresses to MAC addresses, and STP prevents Layer 2 loops. Cisco devices can be configured to synchronize their clocks with an NTP server or another trusted time source. Therefore, NTP is the correct protocol for network time synchronization.

Question 338. Which command is commonly used to test whether a remote IPv4 host is reachable?

1. show version
2. show vlan brief
3. ping
4. show startup-config

Correct Answer: 3. ping

Explanation :-

The ping command is commonly used to test basic IP reachability to a remote host. It sends ICMP Echo Request messages and waits for ICMP Echo Reply messages from the destination. A response provides evidence that the destination is reachable at the IP layer and can also provide basic round-trip-time information. A successful ping does not necessarily prove that every application or service on the destination is functioning. The other commands display device or configuration information rather than actively testing IP reachability. Therefore, ping is the standard command for basic IPv4 connectivity testing.

Question 339. Which protocol is commonly used by Cisco devices to automatically discover neighboring Cisco devices at Layer 2?

1. DHCP
2. CDP
3. DNS
4. NTP

Correct Answer: 2. CDP

Explanation :-

Cisco Discovery Protocol (CDP) is a Cisco proprietary Layer 2 protocol that allows Cisco devices to discover information about directly connected Cisco neighbors. It can provide details such as device ID, platform, capabilities, local interface, remote interface, and management information. CDP does not depend on IP routing and can therefore provide useful neighbor information even when Layer 3 configuration is incomplete. DHCP assigns IP configuration, DNS resolves names, and NTP synchronizes time. Therefore, CDP is the protocol commonly used by Cisco devices to discover directly connected Cisco neighbors.

Question 340. Which command saves the active running configuration to NVRAM?

1. erase startup-config
2. reload
3. show running-config
4. copy running-config startup-config

Correct Answer: 4. copy running-config startup-config

Explanation :-

The copy running-config startup-config command copies the current running configuration from RAM to the startup configuration stored in NVRAM. Saving the configuration ensures that important changes remain available after a reload or power interruption. The show running-config command only displays the active configuration, while erase startup-config removes the saved configuration and reload restarts the device. Cisco administrators commonly save changes after completing configuration work so that the device will restore the intended settings during the next boot. Therefore, copy running-config startup-config is the correct command.