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Sample Questions and Answers
1. Which layer of the OSI model is responsible for routing packets across different networks?
A. Data Link
B. Transport
C. Network
D. Physical
Correct Answer: C. Network
Explanation: The Network layer (Layer 3) is responsible for path determination and logical addressing, allowing packets to be routed between networks using IP addresses.
2. What is the purpose of the ARP protocol?
A. Assign IP addresses dynamically
B. Translate IP addresses to MAC addresses
C. Route packets between networks
D. Encrypt data during transmission
Correct Answer: B. Translate IP addresses to MAC addresses
Explanation: ARP (Address Resolution Protocol) resolves IP addresses to MAC addresses within a local network.
3. Which Cisco command displays the status of interfaces on a switch?
A. show ip interface brief
B. show interfaces status
C. show running-config
D. show vlan
Correct Answer: A. show ip interface brief
Explanation: This command provides a concise summary of all interfaces, including their IP address, status, and protocol state.
4. What is the default administrative distance of a static route in Cisco IOS?
A. 0
B. 1
C. 90
D. 110
Correct Answer: B. 1
Explanation: Static routes have an administrative distance of 1, making them more preferred than routes learned via dynamic protocols like OSPF or EIGRP.
5. What is the function of VLANs in a network?
A. Increase physical ports
B. Encrypt data between switches
C. Segment a broadcast domain
D. Monitor network traffic
Correct Answer: C. Segment a broadcast domain
Explanation: VLANs separate broadcast domains in a switched network, improving performance and security.
6. Which command would you use to save the configuration to NVRAM on a Cisco device?
A. copy running-config startup-config
B. write erase
C. reload
D. show version
Correct Answer: A. copy running-config startup-config
Explanation: This command saves the current running configuration to the startup configuration file in NVRAM.
7. What does the “ping” command verify?
A. IP-to-MAC resolution
B. Network Layer connectivity
C. VLAN configuration
D. Routing protocol operation
Correct Answer: B. Network Layer connectivity
Explanation: The ping command uses ICMP to test IP connectivity between devices.
8. Which protocol is used to automatically assign IP addresses in a network?
A. DNS
B. NAT
C. DHCP
D. ARP
Correct Answer: C. DHCP
Explanation: DHCP (Dynamic Host Configuration Protocol) dynamically assigns IP addresses and configuration to devices on the network.
9. What type of memory on a Cisco router stores the IOS image?
A. RAM
B. NVRAM
C. ROM
D. Flash
Correct Answer: D. Flash
Explanation: The Cisco IOS image is stored in flash memory, which retains its contents after a reboot.
10. Which protocol provides loop prevention in a Layer 2 network?
A. OSPF
B. STP
C. EIGRP
D. CDP
Correct Answer: B. STP
Explanation: The Spanning Tree Protocol (STP) prevents Layer 2 loops in a network by blocking redundant paths.
11. What is the default VLAN on Cisco switches?
A. VLAN 0
B. VLAN 10
C. VLAN 99
D. VLAN 1
Correct Answer: D. VLAN 1
Explanation: By default, all switch ports are assigned to VLAN 1 until configured otherwise.
12. Which command shows the MAC address table on a Cisco switch?
A. show mac-address-table
B. show arp
C. show interface mac
D. show vlan
Correct Answer: A. show mac-address-table
Explanation: This command displays MAC addresses learned on each switch port and the associated VLANs.
13. What is the role of a default gateway in a network?
A. Encrypts outgoing packets
B. Filters incoming packets
C. Routes packets to external networks
D. Assigns IP addresses to clients
Correct Answer: C. Routes packets to external networks
Explanation: The default gateway routes traffic from the local network to destinations outside the subnet.
14. Which cable is used to connect a PC to a Cisco console port?
A. Ethernet crossover
B. Fiber optic
C. Rollover
D. Straight-through
Correct Answer: C. Rollover
Explanation: A rollover cable (console cable) is used to connect to the console port for device management.
15. Which command shows the version of IOS running on a Cisco device?
A. show config
B. show ip route
C. show version
D. show startup
Correct Answer: C. show version
Explanation: This command displays IOS version, system image file, uptime, and device model.
16. What is a common reason for a port to be in an “err-disabled” state?
A. Incorrect IP address
B. Port security violation
C. Duplex mismatch
D. Cable unplugged
Correct Answer: B. Port security violation
Explanation: Security violations such as MAC address mismatches can cause the port to be automatically shut down.
17. What is the main function of a switch in a network?
A. Forward packets based on IP address
B. Translate domain names
C. Segment collision domains
D. Assign VLANs
Correct Answer: C. Segment collision domains
Explanation: Switches reduce collisions by creating separate collision domains per port.
18. What command do you use to enter interface configuration mode?
A. config terminal
B. enable interface
C. interface [type] [number]
D. configure interface
Correct Answer: C. interface [type] [number]
Explanation: This command is used from global configuration mode to enter interface configuration mode.
19. Which protocol does a switch use to learn MAC addresses?
A. ARP
B. CDP
C. STP
D. It learns passively
Correct Answer: D. It learns passively
Explanation: Switches learn MAC addresses by examining the source MAC of incoming frames.
20. What does CDP stand for?
A. Cisco Data Protocol
B. Cisco Discovery Protocol
C. Central Discovery Platform
D. Cisco Device Path
Correct Answer: B. Cisco Discovery Protocol
Explanation: CDP is a Layer 2 Cisco proprietary protocol used to discover neighboring Cisco devices.
21. What is the effect of using the shutdown command on an interface?
A. Sets the interface to DHCP mode
B. Resets interface counters
C. Disables the interface
D. Deletes IP address
Correct Answer: C. Disables the interface
Explanation: The shutdown command administratively brings the interface down.
22. Which feature allows a switch to limit the number of MAC addresses on a port?
A. MAC filtering
B. ARP blocking
C. Port Security
D. DHCP snooping
Correct Answer: C. Port Security
Explanation: Port Security restricts access based on MAC addresses to prevent unauthorized devices.
23. Which protocol is used to synchronize time across network devices?
A. SNMP
B. TFTP
C. NTP
D. DHCP
Correct Answer: C. NTP
Explanation: NTP (Network Time Protocol) ensures devices have consistent system time.
24. What is the purpose of the “reload” command?
A. Restart an interface
B. Save configuration
C. Reboot the device
D. Display logs
Correct Answer: C. Reboot the device
Explanation: The reload command restarts the Cisco device.
25. What protocol replaces Telnet for secure remote access?
A. FTP
B. SSH
C. HTTP
D. TFTP
Correct Answer: B. SSH
Explanation: SSH provides secure, encrypted access to devices, unlike Telnet which transmits in plain text.
26. What is the main difference between a hub and a switch?
A. Hubs are faster
B. Switches operate at Layer 1
C. Switches forward data based on MAC addresses
D. Hubs support VLANs
Correct Answer: C. Switches forward data based on MAC addresses
Explanation: Unlike hubs, which broadcast to all ports, switches intelligently forward based on MAC tables.
27. What is the purpose of a loopback interface on a Cisco router?
A. For traffic monitoring
B. For testing and diagnostics
C. For logging only
D. To connect two routers
Correct Answer: B. For testing and diagnostics
Explanation: Loopback interfaces are logical and always up, useful for routing protocols and management.
28. Which address type is used for one-to-many communication?
A. Unicast
B. Broadcast
C. Multicast
D. Anycast
Correct Answer: C. Multicast
Explanation: Multicast addresses send data to a group of recipients that are part of a multicast group.
29. Which protocol uses Hello packets to establish neighbor relationships?
A. BGP
B. RIP
C. OSPF
D. STP
Correct Answer: C. OSPF
Explanation: OSPF uses Hello packets to discover and maintain neighbor adjacencies.
30. What is the purpose of NAT in networking?
A. Block incoming traffic
B. Encrypt data
C. Translate private to public IP
D. Assign VLANs
Correct Answer: C. Translate private to public IP
Explanation: NAT (Network Address Translation) allows private IP addresses to communicate with public networks like the internet.
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