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Question 221. Which Cisco IOS command is used to create a new VLAN from global configuration mode?

1. vlan 30
2. switchport vlan 30
3. vlan database 30
4. interface vlan 30

Correct Answer: 1. vlan 30

Explanation :-

The vlan 30 command creates VLAN 30 and enters VLAN configuration mode on Cisco IOS switches that support this configuration method. From VLAN configuration mode, an administrator can assign a VLAN name and other relevant settings. The interface vlan 30 command enters the switched virtual interface configuration for VLAN 30 rather than creating the VLAN itself. switchport vlan 30 is not the standard global configuration command for creating a VLAN, and the older vlan database method is not the normal modern IOS approach. VLAN creation is an essential step before assigning access ports to the VLAN.

Question 222. Which protocol is used to discover the MAC address associated with an IPv4 address on a local network?

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

Correct Answer: 3. ARP

Explanation :-

Address Resolution Protocol (ARP) discovers the MAC address associated with a known IPv4 address on a local network. When a device needs to deliver an IPv4 packet to a local destination, it can send an ARP request asking which device owns the target IPv4 address. The destination responds with its MAC address, allowing the sender to construct the appropriate Ethernet frame. DNS resolves hostnames, DHCP provides configuration information, and NTP synchronizes clocks. ARP is therefore the protocol responsible for IPv4-to-MAC address resolution on traditional Ethernet networks.

Question 223. What does the no shutdown command do when applied to a Cisco interface?

1. Removes the interface IP address
2. Enables an administratively disabled interface
3. Deletes the interface configuration
4. Clears the routing table

Correct Answer: 4. Enables an administratively disabled interface

Explanation :-

The no shutdown command enables a Cisco interface that has been administratively disabled with the shutdown command. After applying no shutdown, the interface can become operational if the physical connection and Layer 2 conditions are also correct. The command does not remove the interface’s IP address, erase its configuration, or clear the routing table. Administrators commonly use no shutdown after configuring an interface or when troubleshooting an interface reported as administratively down. The command is entered from interface configuration mode.

Question 224. Which IPv4 prefix length provides 62 usable host addresses in a traditional subnet?

1. /28
2. /25
3. /27
4. /26

Correct Answer: 4. /26

Explanation :-

A /26 IPv4 subnet contains 64 total addresses because six host bits remain. In traditional subnetting, one address is reserved for the network identifier and one for the broadcast address, leaving 62 usable host addresses. A /27 provides 30 usable hosts, /28 provides 14, and /25 provides 126. Understanding the relationship between prefix length and host capacity is important when planning IPv4 networks. The formula for traditional usable hosts is 2^h – 2, where h is the number of host bits.

Question 225. Which Cisco feature can protect a switch port by limiting the number of learned MAC addresses?

1. Port security
2. NTP
3. CDP
4. NAT

Correct Answer: 3. CDP

Explanation :-

The correct feature for limiting the number of MAC addresses that can be learned on a switch port is Port Security, not CDP. Port security allows an administrator to define or limit secure MAC addresses associated with an interface. Depending on the configuration, a switch can take an action when unauthorized MAC addresses are detected. CDP is a neighbor-discovery protocol, NTP synchronizes clocks, and NAT translates IP addresses. Port security is commonly used on access ports to reduce the risk of unauthorized devices connecting to the network.

Question 226. Which protocol uses UDP port 161 for network management queries?

1. DNS
2. SNMP
3. DHCP
4. TFTP

Correct Answer: 2. SNMP

Explanation :-

Simple Network Management Protocol (SNMP) commonly uses UDP port 161 for management queries sent to network devices. SNMP allows management systems to retrieve information such as interface status, traffic counters, and system statistics. SNMP traps and informs use different communication behavior and commonly involve UDP port 162 for notifications. DNS commonly uses UDP port 53, DHCP uses UDP ports 67 and 68, and TFTP uses UDP port 69. Knowing common protocol ports is useful for troubleshooting, access-control configuration, and certification exam questions involving network services.

Question 227. Which type of IPv6 address is used for communication with all nodes on the local link?

1. FF02::1
2. FE80::1
3. FC00::1
4. 2001::1

Correct Answer: 1. FF02::1

Explanation :-

FF02::1 is the IPv6 multicast address representing all nodes on the local link. IPv6 uses multicast extensively because it does not use traditional broadcast addressing. The FF00::/8 prefix identifies multicast addresses, and the FF02 scope indicates link-local scope. FE80::/10 identifies link-local unicast addresses, FC00::/7 is used for unique local addresses, and 2000::/3 represents global unicast space. Understanding common IPv6 multicast addresses is important for interpreting Neighbor Discovery and other IPv6 control traffic.

Question 228. Which command displays the IPv4 routing protocols configured on a Cisco router?

1. show ip interface brief
2. show ip protocols
3. show ip route
4. show protocols

Correct Answer: 4. show protocols

Explanation :-

The command commonly used to display information about routing protocols configured on a Cisco router is show ip protocols, not show protocols. show ip protocols provides information such as active routing protocols, network statements, timers, and other protocol-specific parameters. show ip route displays the routing table, while show ip interface brief provides interface summaries. The distinction is important because show protocols provides broader interface protocol information rather than the detailed IPv4 routing-protocol configuration. When troubleshooting dynamic routing, show ip protocols is particularly useful.

Question 229. Which switching technique stores the entire Ethernet frame before forwarding it?

1. Cut-through
2. Fast switching
3. Store-and-forward
4. Process switching

Correct Answer: 3. Store-and-forward

Explanation :-

Store-and-forward switching receives the complete Ethernet frame before forwarding it to the destination interface. Because the switch receives the entire frame, it can perform a frame check sequence (FCS) or CRC integrity check before forwarding. This can prevent corrupted frames from being propagated through the network. Cut-through switching begins forwarding earlier, after enough information has been received to identify the destination. Process switching and fast switching are primarily associated with Layer 3 forwarding methods rather than Ethernet switching methods. Store-and-forward is therefore the switching method characterized by receiving the complete frame first.

Question 230. Which address is used by a router to identify the next device toward a remote destination?

1. Destination MAC address only
2. Default VLAN
3. Next-hop IP address
4. Broadcast address

Correct Answer: 4. Broadcast address

Explanation :-

The correct concept for identifying the next router toward a remote destination is the next-hop IP address, not a broadcast address. A routing table can specify a next-hop IP address that identifies where a packet should be sent next. On an Ethernet network, the router may use ARP to resolve that next-hop IPv4 address to a MAC address before transmitting the frame. Broadcast addresses are used for one-to-all delivery within a broadcast domain and are not used as normal next-hop routing destinations. Next-hop information is fundamental to Layer 3 packet forwarding.

Question 231. Which protocol provides automatic IP address assignment to network clients?

1. DHCP
2. SSH
3. SNMP
4. ARP

Correct Answer: 2. DHCP

Explanation :-

Dynamic Host Configuration Protocol (DHCP) automatically provides clients with network configuration information. Depending on the DHCP scope and configuration, a client can receive an IP address, subnet mask, default gateway, DNS server addresses, and other parameters. SSH provides secure remote management, SNMP provides monitoring and management information, and ARP resolves IPv4 addresses to MAC addresses. DHCP reduces manual configuration requirements and helps administrators manage address allocation centrally. It is widely used in enterprise, home, and service-provider environments for automatically configuring hosts.

Question 232. Which Cisco IOS command shows the current active configuration of a device?

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

Correct Answer: 3. show running-config

Explanation :-

The show running-config command displays the configuration currently active on the Cisco device and stored in RAM. It includes configuration changes that have been made during the current session, even if they have not yet been saved to NVRAM. The show startup-config command displays the saved configuration that is used during startup. show flash displays files in flash memory, while show version provides software and hardware information. Administrators commonly compare the running and startup configurations to determine whether recent configuration changes have been saved.

Question 233. Which IPv4 address class traditionally contains the private 10.0.0.0/8 range?

1. Class A
2. Class B
3. Class C
4. Class D

Correct Answer: 4. Class D

Explanation :-

The correct answer under the traditional classful IPv4 system is Class A for the 10.0.0.0/8 private range. Class A addresses historically used a first octet from 1 through 126, with the default mask 255.0.0.0. The private 10.0.0.0/8 range occupies part of this traditional Class A space. Class B historically covered 128.0.0.0 through 191.255.255.255, Class C covered 192.0.0.0 through 223.255.255.255, and Class D is associated with multicast addressing. Modern networks use CIDR rather than relying on classful addressing.

Question 234. Which command displays the VLAN assignment and status of switch ports in a concise format?

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

Correct Answer: 1. show vlan brief

Explanation :-

The show vlan brief command displays VLAN information and identifies access ports associated with each VLAN. It is useful when verifying whether switch ports have been assigned to the correct VLAN. The command also shows VLAN IDs, names, and status in a concise format. show ip route displays Layer 3 routing information, show arp displays IPv4-to-MAC mappings, and show version provides system and software information. VLAN verification is an important troubleshooting step when hosts connected to a switch cannot communicate as expected within their intended Layer 2 segment.

Question 235. Which protocol is commonly used to securely manage a Cisco device remotely?

1. TFTP
2. Telnet
3. SSH
4. FTP

Correct Answer: 3. SSH

Explanation :-

Secure Shell (SSH) is commonly used for secure remote management of Cisco devices. SSH encrypts the management session, including authentication credentials and commands, helping protect sensitive administrative information from interception. Telnet also supports remote CLI access but does not provide equivalent session encryption. TFTP and FTP are file-transfer protocols rather than interactive secure management protocols. SSH is typically preferred for remote administration because it provides confidentiality and authentication capabilities. Cisco devices require appropriate configuration, including cryptographic keys and user authentication, before SSH can be used successfully.

Question 236. Which device forwards Ethernet frames based primarily on destination MAC addresses?

1. Router
2. Switch
3. Firewall
4. Modem

Correct Answer: 2. Switch

Explanation :-

A traditional Layer 2 switch forwards Ethernet frames based primarily on destination MAC addresses. It maintains a MAC address table that maps learned source MAC addresses to switch interfaces. When a frame arrives, the switch examines the destination MAC address and determines the appropriate forwarding interface when the address is known. Routers primarily make forwarding decisions using IP addresses, while firewalls can make decisions using multiple attributes depending on their capabilities. A modem performs functions related to converting or transporting signals over a particular access medium. Switches are therefore the standard Layer 2 forwarding devices.

Question 237. Which command displays the IPv6 addresses configured on a Cisco interface?

1. show ipv6 interface
2. show ip interface brief
3. show ipv6 route
4. show interfaces status

Correct Answer: 4. show interfaces status

Explanation :-

The correct command for directly displaying IPv6 addresses configured on an interface is show ipv6 interface, not show interfaces status. The show ipv6 interface command provides detailed IPv6 information, including assigned IPv6 addresses, interface state, and IPv6-related parameters. show ipv6 route displays the IPv6 routing table. show ip interface brief focuses on IPv4 interface information, while show interfaces status provides general Layer 2 interface status. When troubleshooting IPv6 addressing on a Cisco device, show ipv6 interface is the appropriate command to inspect the interface’s IPv6 configuration.

Question 238. Which NAT method maps one private IPv4 address to one specific public IPv4 address?

1. PAT
2. Static NAT
3. Dynamic routing
4. DHCP

Correct Answer: 2. Static NAT

Explanation :-

Static NAT creates a permanent one-to-one mapping between an internal private IPv4 address and a specific public IPv4 address. This is useful when an internal host must be consistently reachable through the same public address. PAT allows many internal hosts to share one public address by distinguishing connections with port numbers. Dynamic NAT uses a pool of public addresses and assigns mappings as needed. DHCP provides IP configuration rather than address translation. Static NAT is therefore the NAT method associated with a fixed one-to-one address mapping.

Question 239. Which protocol is used by routers to exchange routing information dynamically within an OSPF network?

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

Correct Answer: 1. OSPF

Explanation :-

Open Shortest Path First (OSPF) is a link-state interior gateway routing protocol that allows routers within an OSPF domain to exchange information about network topology. OSPF routers form neighbor relationships and exchange link-state information, which is used to build a link-state database. Each router then calculates shortest paths through the topology. FTP is used for file transfer, DHCP provides host configuration, and SNMP supports network management. OSPF is therefore the protocol responsible for dynamically exchanging routing information and calculating routes within an OSPF-enabled network.

Question 240. Which command can be used to trace the Layer 3 path packets take toward a destination?

1. ping
2. show arp
3. traceroute
4. show mac address-table

Correct Answer: 3. traceroute

Explanation :-

The traceroute command identifies the Layer 3 path toward a destination by sending packets with varying TTL values and observing responses from intermediate routers. This allows administrators to identify the sequence of routed hops between the source and destination and can help locate where connectivity problems occur. The ping command tests basic reachability but does not normally provide the complete path. show arp displays local IPv4-to-MAC mappings, while show mac address-table displays Layer 2 MAC information on switches. Traceroute is therefore the appropriate tool for path discovery and hop-by-hop troubleshooting.