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Question 141. Which Cisco IOS command is used to enter global configuration mode from privileged EXEC mode?

1. configure terminal
2. enable
3. configure memory
4. terminal monitor

Correct Answer: 1. configure terminal

Explanation :-

The configure terminal command moves a Cisco IOS device from privileged EXEC mode into global configuration mode. Global configuration mode is used to make configuration changes that affect the overall operation of the device, such as setting the hostname, configuring routing protocols, creating VLANs, or modifying security settings. The enable command is used to enter privileged EXEC mode from user EXEC mode. configure memory is associated with loading configuration information rather than entering terminal-based configuration mode, while terminal monitor displays system messages on a terminal session. Therefore, configure terminal is the appropriate command for entering global configuration mode.

Question 142. Which IPv4 address range is reserved for private Class A addressing?

1. 172.16.0.0/12
2. 192.168.0.0/16
3. 10.0.0.0/8
4. 127.0.0.0/8

Correct Answer: 3. 10.0.0.0/8

Explanation :-

The IPv4 private address range traditionally associated with Class A private addressing is 10.0.0.0/8. Addresses in this range are intended for use within private networks and are not routable across the public Internet. The other private ranges are 172.16.0.0/12 and 192.168.0.0/16. The 127.0.0.0/8 range is reserved for loopback addresses. Private addressing is commonly used inside enterprise, home, and service-provider networks, often together with Network Address Translation (NAT) when hosts need to communicate with public Internet destinations.

Question 143. Which Cisco IOS command displays the current configuration stored in RAM?

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

Correct Answer: 2. show running-config

Explanation :-

The show running-config command displays the active configuration currently stored in RAM and being used by the Cisco device. Configuration changes made during a session are initially reflected in the running configuration. To preserve those changes across a reload, the configuration must be copied to startup configuration in NVRAM. The show startup-config command displays the saved configuration, while show version provides system and software information. The show flash command displays information about files stored in flash memory. Therefore, show running-config is the correct command for viewing the active configuration.

Question 144. What is the primary function of a default gateway for an IPv4 host?

1. Assign an IP address automatically
2. Translate private addresses into public addresses
3. Resolve domain names into IP addresses
4. Forward traffic destined for remote networks

Correct Answer: 4. Forward traffic destined for remote networks

Explanation :-

A default gateway provides an IPv4 host with a next-hop device, normally a router, for destinations outside the host’s local subnet. When a host determines that a destination is on another network, it sends the packet to its configured default gateway. The router then determines how to forward the packet toward the destination. DHCP can automatically provide hosts with addressing information, NAT can translate addresses, and DNS resolves names to IP addresses, but these are different functions. The default gateway is therefore essential for communication between a local network and remote networks.

Question 145. Which IPv6 address type is used for communication with the nearest member of a group according to routing distance?

1. Anycast
2. Multicast
3. Unicast
4. Broadcast

Correct Answer: 1. Anycast

Explanation :-

An IPv6 anycast address identifies multiple interfaces, typically on different devices, and packets sent to that address are delivered to the nearest interface according to the routing protocol’s distance or metric. Anycast can be useful for distributed services because clients can reach a nearby instance of a service. IPv6 does not use broadcast addressing. Unicast identifies a single interface, while multicast identifies a group of interfaces and delivers traffic to members of that group. Anycast provides a mechanism for reaching one member of a group based on routing considerations.

Question 146. Which protocol provides secure remote access to the Cisco IOS command-line interface?

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

Correct Answer: 3. SSH

Explanation :-

Secure Shell (SSH) provides encrypted remote access to the Cisco IOS command-line interface. SSH protects authentication credentials and management traffic from being transmitted in plain text. Telnet also provides remote CLI access, but its traffic is not encrypted and can expose credentials to interception. FTP and TFTP are primarily used for file transfers rather than interactive device management. SSH commonly uses TCP port 22 and is preferred for secure remote administration of Cisco network devices. Proper SSH configuration normally involves setting a hostname, domain name, authentication credentials, and RSA keys.

Question 147. What is the purpose of a subnet mask in an IPv4 network?

1. Identify the DNS server
2. Determine the network and host portions of an IP address
3. Identify the physical MAC address
4. Select the default routing protocol

Correct Answer: 2. Determine the network and host portions of an IP address

Explanation :-

An IPv4 subnet mask determines which bits of an IP address represent the network portion and which bits represent the host portion. This information allows devices to determine whether a destination is on the local subnet or requires forwarding through a router. For example, a /24 prefix corresponds to the subnet mask 255.255.255.0, leaving eight bits for host addressing. A subnet mask does not identify a MAC address, DNS server, or routing protocol. Correct subnetting is fundamental to IP communication and efficient network address allocation.

Question 148. Which switching method begins forwarding a frame before the entire frame has been received?

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

Correct Answer: 4. Cut-through switching

Explanation :-

Cut-through switching allows a switch to begin forwarding a frame after reading enough of the frame to determine its destination, rather than waiting for the entire frame to arrive. This can reduce forwarding latency because transmission begins earlier. Store-and-forward switching, by contrast, receives the complete frame before forwarding it and can perform a full frame integrity check. Fragment-free switching is a variation that waits for the first 64 bytes before forwarding. Cut-through switching is therefore characterized by lower forwarding latency, although it may forward corrupted frames that a store-and-forward switch could detect.

Question 149. Which Cisco IOS command displays a concise summary of interface IP addresses and their operational status?

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

Correct Answer: 1. show ip interface brief

Explanation :-

The show ip interface brief command provides a concise overview of interfaces, including their assigned IP addresses and the status of the interface and line protocol. It is commonly used for quick troubleshooting and verification. The output helps administrators identify interfaces that are administratively down, physically down, or operational. show ip route displays the routing table rather than an interface summary. Other interface commands provide more detailed information, but show ip interface brief is specifically designed to provide a compact overview of IP addressing and interface status.

Question 150. Which protocol is responsible for translating domain names such as example.com into IP addresses?

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

Correct Answer: 2. DNS

Explanation :-

The Domain Name System (DNS) translates human-readable domain names into IP addresses that network devices can use for communication. For example, a client can query DNS to determine the IP address associated with a web server’s domain name. DHCP is used to provide hosts with configuration information such as IP addresses and default gateways. SNMP is used for network monitoring and management, while NTP synchronizes device clocks. DNS is therefore the protocol responsible for name resolution. DNS commonly uses UDP port 53 for standard queries, although TCP can also be used for certain operations.

Question 151. Which type of Ethernet cable is traditionally used to connect a PC directly to a switch?

1. Rollover cable
2. Crossover cable
3. Console cable
4. Straight-through cable

Correct Answer: 4. Straight-through cable

Explanation :-

A straight-through Ethernet cable traditionally connects unlike Ethernet device types, such as a PC to a switch or a router to a switch. The transmit and receive pairs remain aligned between the corresponding connector standards. A crossover cable was traditionally used when connecting similar device types, such as switch-to-switch or PC-to-PC connections, although modern devices commonly support Auto-MDIX and can automatically adjust for cable type. A rollover cable is associated with console connections to Cisco devices. Therefore, the traditional cable type for connecting a PC directly to a switch is a straight-through cable.

Question 152. Which protocol is commonly used by network devices to synchronize their clocks?

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

Correct Answer: 1. NTP

Explanation :-

Network Time Protocol (NTP) is used to synchronize the clocks of network devices with a reliable time source. Accurate time is important for troubleshooting, logging, security analysis, authentication systems, and correlating events across multiple devices. Cisco devices can be configured to use NTP servers so that their system clocks remain synchronized. FTP is used for file transfers, ARP maps IPv4 addresses to MAC addresses on local networks, and ICMP is used for network control and diagnostic messaging. NTP therefore provides the time synchronization function required for consistent device timestamps.

Question 153. What happens when a switch receives an Ethernet frame with an unknown destination MAC address?

1. The switch drops the frame immediately
2. The switch sends the frame only to the default gateway
3. The switch floods the frame out other ports in the same VLAN
4. The switch converts the frame into an IP packet

Correct Answer: 3. The switch floods the frame out other ports in the same VLAN

Explanation :-

When a switch receives a frame whose destination MAC address is not present in its MAC address table, it treats the frame as an unknown unicast. The switch floods the frame out all other appropriate ports within the same VLAN, except the port on which the frame was received. If the destination device responds, the switch can learn its source MAC address and associate it with the incoming port. This learning process gradually builds the MAC address table and reduces unnecessary flooding. The switch does not send an unknown unicast only to the default gateway.

Question 154. Which protocol maps an IPv4 address to the corresponding MAC address on a local network?

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

Correct Answer: 2. ARP

Explanation :-

Address Resolution Protocol (ARP) is used in IPv4 networks to determine the MAC address associated with a known IPv4 address on the local network. A host can send an ARP request asking which device owns a particular IPv4 address. The device with that address responds with its MAC address, allowing the sender to construct an Ethernet frame for local delivery. DNS performs name resolution, DHCP provides network configuration, and NTP synchronizes clocks. IPv6 does not use ARP; instead, it uses Neighbor Discovery Protocol (NDP) for similar neighbor-address resolution functions.

Question 155. Which routing protocol is classified as a link-state routing protocol?

1. RIP
2. OSPF
3. EIGRP
4. BGP

Correct Answer: 2. OSPF

Explanation :-

Open Shortest Path First (OSPF) is a link-state interior gateway protocol. OSPF routers exchange link-state information and construct a topology database representing the network. They then use the Shortest Path First algorithm to calculate optimal paths. RIP is a distance-vector protocol that uses hop count as its metric. EIGRP is commonly described as an advanced distance-vector or hybrid protocol, while BGP is a path-vector protocol used primarily for inter-autonomous-system routing. OSPF is widely deployed in enterprise networks because it supports hierarchical design, fast convergence, and scalable routing through areas.

Question 156. Which command saves the current running configuration to NVRAM on a Cisco device?

1. copy startup-config running-config
2. copy flash running-config
3. copy running-config startup-config
4. copy tftp startup-config

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

Explanation :-

The copy running-config startup-config command saves the active configuration in RAM to the startup configuration stored in NVRAM. Saving the configuration is important because the running configuration is lost when a device is reloaded if it has not been saved. The command copies the current operational settings into the configuration file used during the next boot process. The reverse direction, copy startup-config running-config, loads the saved configuration into the running configuration. Therefore, copy running-config startup-config is the appropriate command for preserving configuration changes.

Question 157. Which IPv4 address is a valid private address?

1. 8.8.8.8
2. 172.20.15.10
3. 169.254.10.5
4. 224.0.0.1

Correct Answer: 2. 172.20.15.10

Explanation :-

The IPv4 address 172.20.15.10 falls within the private 172.16.0.0/12 range, which extends from 172.16.0.0 through 172.31.255.255. Private IPv4 addresses are intended for internal network use and are not directly routable across the public Internet. 8.8.8.8 is a public address, 169.254.10.5 belongs to the IPv4 link-local range, and 224.0.0.1 is a multicast address. Recognizing private address ranges is important when designing IPv4 networks and configuring NAT or other mechanisms for communication between private and public address spaces.

Question 158. Which device primarily operates at Layer 2 of the OSI model and forwards frames based on MAC addresses?

1. Router
2. Firewall
3. Switch
4. DNS server

Correct Answer: 3. Switch

Explanation :-

A traditional Ethernet switch primarily operates at Layer 2, the Data Link layer, and forwards Ethernet frames using destination MAC addresses. The switch learns source MAC addresses from incoming frames and stores them in its MAC address table. A router primarily operates at Layer 3 and forwards packets based on IP addresses and routing information. Firewalls can operate across multiple layers depending on their capabilities, while a DNS server provides name-resolution services. Understanding the distinction between Layer 2 switching and Layer 3 routing is fundamental to designing and troubleshooting Cisco networks.

Question 159. Which command displays detailed information about the interfaces on a Cisco device, including errors and packet statistics?

1. show interfaces
2. show vlan brief
3. show ip route
4. show mac address-table

Correct Answer: 1. show interfaces

Explanation :-

The show interfaces command displays detailed information about device interfaces, including operational status, bandwidth, packet counters, errors, collisions, encapsulation information, and other interface statistics. This makes it particularly useful for troubleshooting connectivity and performance problems. show vlan brief provides VLAN information, show ip route displays the routing table, and show mac address-table displays Layer 2 MAC address information. When investigating packet loss, interface errors, duplex issues, or physical connectivity problems, administrators commonly use show interfaces to examine detailed interface statistics.

Question 160. What is the primary purpose of VLANs on a Cisco switch?

1. Increase the physical speed of Ethernet ports
2. Replace IP addressing
3. Encrypt Ethernet frames
4. Logically separate devices into different broadcast domains

Correct Answer: 4. Logically separate devices into different broadcast domains

Explanation :-

Virtual LANs (VLANs) logically divide a physical switch infrastructure into separate Layer 2 broadcast domains. Devices assigned to different VLANs are logically separated even when they are connected to the same physical switch. Communication between VLANs requires a Layer 3 device, such as a router or multilayer switch. VLANs do not inherently encrypt Ethernet frames or replace IP addressing, and they do not directly increase the physical speed of switch ports. VLAN segmentation can improve network organization, security boundaries, and broadcast-domain management in a switched network.