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Question 381. Which command displays a concise summary of IPv4 addresses and interface status on a Cisco router?

1. show running-config
2. show ip route
3. show version
4. show ip interface brief

Correct Answer: 4. show ip interface brief

Explanation :-

The show ip interface brief command provides a concise summary of interfaces, their assigned IPv4 addresses, administrative status, and line protocol status. It is particularly useful during initial troubleshooting because an administrator can quickly identify interfaces that are administratively down or whose line protocol is down. The show running-config command displays the active configuration, show ip route displays the IPv4 routing table, and show version provides software and hardware information. Therefore, show ip interface brief is the most appropriate command when a quick overview of IPv4 addressing and interface operational status is required.

Question 382. Which protocol is used by routers to exchange routing information dynamically within an OSPF-enabled network?

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

Correct Answer: 2. OSPF

Explanation :-

Open Shortest Path First (OSPF) is a dynamic link-state routing protocol used by routers to exchange routing information within an OSPF domain. OSPF routers form neighbor relationships, exchange link-state information, maintain a link-state database, and calculate routes using the Shortest Path First algorithm. DHCP provides host configuration, ARP resolves IPv4 addresses to MAC addresses, and DNS provides name resolution. OSPF supports features such as areas, cost-based path selection, and authentication options depending on the implementation. Therefore, OSPF is the protocol responsible for dynamically exchanging routing information in the described network.

Question 383. Which IPv4 address is the network address for the subnet 192.168.50.64/26?

1. 192.168.50.64
2. 192.168.50.65
3. 192.168.50.126
4. 192.168.50.127

Correct Answer: 1. 192.168.50.64

Explanation :-

A /26 subnet uses the mask 255.255.255.192, creating blocks of 64 addresses in the final octet. The subnet boundaries are therefore 0, 64, 128, and 192. For the subnet beginning at 192.168.50.64, the network address is 192.168.50.64, the usable host range is 192.168.50.65 through 192.168.50.126, and the broadcast address is 192.168.50.127. Because the network address identifies the subnet itself and is not normally assigned to a host, 192.168.50.64 is the correct answer.

Question 384. Which protocol is used to synchronize the clocks of network devices?

1. FTP
2. SNMP
3. NTP
4. TFTP

Correct Answer: 3. NTP

Explanation :-

Network Time Protocol (NTP) is used to synchronize the clocks of network devices and other systems across an IP network. Accurate time synchronization is important for logging, troubleshooting, authentication mechanisms, certificates, and event correlation. NTP allows devices to obtain time from configured time sources and maintain their clocks within an appropriate level of accuracy. SNMP is primarily used for network monitoring and management, while FTP and TFTP are file-transfer protocols. Cisco devices can be configured as NTP clients or, in appropriate designs, as NTP servers. Therefore, NTP is the protocol used for network time synchronization.

Question 385. What is the purpose of the subnet mask in an IPv4 address?

1. It identifies the device’s MAC address
2. It determines the DNS server
3. It encrypts IP packets
4. It separates the network portion from the host portion

Correct Answer: 4. It separates the network portion from the host portion

Explanation :-

An IPv4 subnet mask identifies which bits of an IPv4 address represent the network portion and which bits represent the host portion. Devices use this information to determine whether a destination is on the local subnet or must be reached through a router. For example, a /24 mask corresponds to 255.255.255.0, meaning the first 24 bits identify the network and the remaining 8 bits identify hosts within that network. A subnet mask does not identify a device’s MAC address, select a DNS server, or provide encryption. Therefore, separating network and host portions is the primary purpose of an IPv4 subnet mask.

Question 386. Which Cisco IOS command displays the ARP cache of a device?

1. show arp
2. show cdp neighbors
3. show vlan brief
4. show ip route

Correct Answer: 1. show arp

Explanation :-

The show arp command displays the Address Resolution Protocol cache on a Cisco device. The output can include IPv4 addresses, corresponding MAC addresses, address types, and associated interfaces. ARP information helps a device determine the Layer 2 destination needed to deliver IPv4 packets on an Ethernet network. show cdp neighbors displays directly connected Cisco neighbor information, show vlan brief summarizes VLANs, and show ip route displays routing information. Because the ARP cache contains IPv4-to-MAC mappings, show arp is the appropriate command for examining those mappings.

Question 387. Which type of IPv4 address is designed to be reachable across the public Internet?

1. Loopback
2. Link-local
3. Public
4. Private

Correct Answer: 3. Public

Explanation :-

A public IPv4 address is globally routable and can be used for communication across the public Internet, subject to routing, security policies, and other requirements. Private IPv4 addresses, such as those in 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16, are intended for internal networks and are not directly routable across the public Internet. Loopback addresses are used by a device to communicate with itself, while IPv4 link-local addresses in 169.254.0.0/16 are intended for local-link communication. Therefore, a public IPv4 address is the address type designed for Internet-routable communication.

Question 388. Which Cisco technology can bundle multiple Ethernet interfaces to provide increased bandwidth and redundancy?

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

Correct Answer: 1. EtherChannel

Explanation :-

EtherChannel combines multiple physical Ethernet interfaces into a single logical interface. This provides increased aggregate bandwidth and redundancy while simplifying how the bundled links are represented to Layer 2 protocols. EtherChannel can be implemented using negotiation protocols such as LACP or PAgP, depending on the device and configuration. DHCP snooping is a security feature that helps control DHCP traffic, port security limits MAC address usage on switch ports, and NAT translates addresses between different address spaces. Therefore, EtherChannel is the Cisco technology used to combine multiple Ethernet links into a logical connection.

Question 389. Which command can display information about the neighboring device connected to a specific Cisco switch port?

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

Correct Answer: 3. show cdp neighbors

Explanation :-

The show cdp neighbors command displays information learned through Cisco Discovery Protocol from directly connected Cisco devices. The output can identify the neighboring device, local interface, remote port, platform, and capabilities. This is useful for verifying physical topology and determining what Cisco device is connected to a particular interface. The show ip route command provides routing information, show startup-config displays the saved configuration, and show vlan brief summarizes VLAN membership. Therefore, show cdp neighbors is the appropriate command when an administrator needs information about a directly connected Cisco neighbor.

Question 390. Which protocol provides connection-oriented, reliable transport for applications?

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

Correct Answer: 4. TCP

Explanation :-

Transmission Control Protocol (TCP) provides connection-oriented and reliable transport between applications. TCP establishes a logical connection 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. IP operates at the network layer and provides packet delivery between networks, while ICMP is primarily used for network control and diagnostic messages. Many traditional application protocols use TCP when reliable transport is required. Therefore, TCP is the transport-layer protocol that provides connection-oriented and reliable delivery.

Question 391. Which IPv6 address prefix identifies global unicast addresses?

1. 2000::/3
2. FE80::/10
3. FF00::/8
4. FC00::/7

Correct Answer: 1. 2000::/3

Explanation :-

The IPv6 2000::/3 prefix is used for global unicast addressing. Global unicast addresses are designed for communication across IPv6 networks and can be routed globally. The FE80::/10 range is used for link-local unicast addresses, FF00::/8 is used for multicast addresses, and FC00::/7 is associated with unique local addresses. Understanding these major IPv6 address categories is important for identifying how an address can be used and whether it is intended for local or broader routing. Therefore, 2000::/3 is the correct prefix for IPv6 global unicast addresses.

Question 392. Which Cisco IOS command displays the current active configuration?

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

Correct Answer: 2. show running-config

Explanation :-

The show running-config command displays the configuration currently active on a Cisco device. This configuration is maintained in RAM and includes changes made during the current operating session, including changes that may not yet have been saved. The show startup-config command displays the configuration stored in NVRAM and normally loaded after a reboot. show flash provides information about files stored in flash memory, while show version displays system and software information. Reviewing the running configuration is important when troubleshooting or verifying current settings. Therefore, show running-config is the correct command for displaying the active configuration.

Question 393. Which device makes forwarding decisions primarily using destination IP addresses?

1. Hub
2. Layer 2 switch
3. Router
4. Repeater

Correct Answer: 3. Router

Explanation :-

A router primarily makes Layer 3 forwarding decisions using destination IP addresses and its routing table. When a packet arrives, the router examines the destination IP address, identifies the best matching route, and forwards the packet through the appropriate interface or next hop. A traditional Layer 2 switch forwards Ethernet frames using MAC addresses, while a hub and repeater operate primarily at the physical layer and do not make IP routing decisions. Multilayer switches can also perform Layer 3 forwarding, but the router is the device class specifically designed for routing between IP networks. Therefore, a router is the correct answer.

Question 394. Which protocol is commonly used to securely transfer files using an SSH-based connection?

1. TFTP
2. SFTP
3. HTTP
4. Telnet

Correct Answer: 4. SFTP

Explanation :-

Secure File Transfer Protocol (SFTP) provides secure file transfer through an SSH-based connection. It encrypts authentication credentials and file-transfer data, making it suitable when confidentiality and secure remote file management are required. TFTP is a lightweight file-transfer protocol that does not provide the same authentication and encryption features. HTTP is an application-layer web protocol, while Telnet provides remote terminal access without the encryption protections of SSH. SFTP should also be distinguished from FTPS, which uses TLS rather than SSH. Therefore, SFTP is the protocol among these choices that securely transfers files using SSH.

Question 395. Which command displays the MAC addresses that a Cisco switch has learned on its interfaces?

1. show mac address-table
2. show ip interface brief
3. show ip route
4. show version

Correct Answer: 2. show mac address-table

Explanation :-

The show mac address-table command displays MAC addresses learned by a Cisco switch and associates them with VLANs and switch interfaces. Switches dynamically learn source MAC addresses from incoming Ethernet frames and use the resulting table to make forwarding decisions. show ip interface brief summarizes IP addressing and interface status, show ip route displays Layer 3 routing information, and show version provides system information. Examining the MAC address table is especially useful when troubleshooting switching behavior, verifying where a device is connected, or confirming that the switch has learned the expected MAC address. Therefore, show mac address-table is correct.

Question 396. Which feature prevents a switch port from accepting more than a configured number of secure MAC addresses?

1. NTP
2. Port security
3. OSPF
4. DNS

Correct Answer: 2. Port security

Explanation :-

Switch port security can limit the number of secure MAC addresses that are permitted on a switch interface. An administrator can configure a maximum number of secure addresses and specify how the switch should respond when a violation occurs. This feature is commonly applied to access ports where the expected number of connected devices is known. NTP synchronizes device clocks, OSPF provides dynamic routing, and DNS provides name resolution. Port security therefore directly addresses control over which MAC addresses and how many MAC addresses can be associated with a switch port.

Question 397. Which command saves the running configuration to the startup configuration?

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

Correct Answer: 3. copy running-config startup-config

Explanation :-

The copy running-config startup-config command saves the currently active configuration to the startup configuration stored in NVRAM. Saving the configuration ensures that changes made during the current session are preserved when the device is restarted. The reverse command, copy startup-config running-config, loads the saved configuration into the active configuration. erase startup-config removes the saved configuration, while reload restarts the device. Because unsaved changes in the running configuration can be lost after a reboot, administrators should save important configuration changes using the appropriate copy command.

Question 398. Which protocol is used by IPv6 hosts and routers for neighbor discovery instead of ARP?

1. NDP
2. FTP
3. DHCP
4. SNMP

Correct Answer: 1. NDP

Explanation :-

IPv6 uses Neighbor Discovery Protocol (NDP), which operates through ICMPv6 messages, to perform functions that include discovering neighboring devices, resolving link-layer addresses, and learning router information. NDP replaces the traditional role of ARP used in IPv4 networks. Neighbor Solicitation and Neighbor Advertisement messages are among the mechanisms used for address resolution and neighbor discovery. FTP is a file-transfer protocol, DHCP provides network configuration, and SNMP supports network management. Therefore, NDP is the protocol used by IPv6 devices for neighbor discovery and related functions that would commonly involve ARP in IPv4.

Question 399. Which IPv4 address is reserved for limited broadcast traffic?

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

Correct Answer: 3. 255.255.255.255

Explanation :-

The IPv4 address 255.255.255.255 represents the limited broadcast address. Packets sent to this address are intended for all IPv4 hosts on the local network segment and are not routed by IPv4 routers. The address 0.0.0.0 can represent an unspecified address in appropriate contexts, 127.0.0.1 is the loopback address, and 224.0.0.1 is an IPv4 multicast address used to identify all hosts on a local subnet that participate in the relevant multicast function. Therefore, 255.255.255.255 is the correct limited broadcast address.

Question 400. Which Cisco IOS command displays detailed operational statistics for interfaces?

1. show interfaces
2. show vlan brief
3. show startup-config
4. show cdp neighbors

Correct Answer: 1. show interfaces

Explanation :-

The show interfaces command provides detailed operational information and statistics for device interfaces. Depending on the interface, the output can include administrative and line-protocol status, hardware information, IP configuration details, packet counters, errors, collisions, bandwidth, and other interface statistics. show vlan brief summarizes VLAN configuration, show startup-config displays the saved configuration, and show cdp neighbors provides information about directly connected Cisco devices. Because detailed interface health and traffic statistics are required when troubleshooting physical or logical interface problems, show interfaces is the appropriate command.