[2024] CCNA Interview Questions on Switch Configuration

Switch configuration is a fundamental skill for any IT professional preparing for the Cisco Certified Network Associate (CCNA) exam. Switches play a critical role in managing network traffic and ensuring efficient communication between devices on a network. Mastery of switch configuration not only helps in passing the CCNA exam but also equips you with practical knowledge for real-world network management. This article provides a comprehensive list of common interview questions related to switch configuration, along with detailed answers to help you prepare effectively.

1. What is a VLAN, and why is it used?

A Virtual Local Area Network (VLAN) is a logical grouping of devices within a network that allows them to communicate as if they are on the same physical network, even if they are not. VLANs are used to segment network traffic, improve security, and manage broadcast domains more efficiently. By isolating traffic within VLANs, you can reduce congestion and improve overall network performance.

2. How do you configure a VLAN on a Cisco switch?

To configure a VLAN on a Cisco switch, follow these steps:

1. Enter global configuration mode by typing configure terminal.
2. Create the VLAN by typing vlan [VLAN_ID], where [VLAN_ID] is the VLAN number.
3. Assign a name to the VLAN using the name [VLAN_NAME] command.
4. Exit VLAN configuration mode by typing exit.
5. Assign switch ports to the VLAN using the interface [INTERFACE_ID] command followed by switchport mode access and switchport access vlan [VLAN_ID].

3. What is the purpose of the switchport mode trunk command?

The switchport mode trunk command is used to configure a switch port as a trunk port. A trunk port is used to carry traffic for multiple VLANs between switches. This allows VLAN information to be preserved as traffic traverses the network, enabling communication between devices on different VLANs.

4. How do you verify VLAN configuration on a Cisco switch?

To verify VLAN configuration, you can use the following commands:

• show vlan brief: Displays a summary of all VLANs configured on the switch.
• show vlan id [VLAN_ID]: Provides detailed information about a specific VLAN.
• show interfaces switchport: Displays information about switch port modes and VLAN assignments.

5. What is a VLAN trunking protocol (VTP)?

VLAN Trunking Protocol (VTP) is a Cisco proprietary protocol used to manage VLANs across multiple switches. VTP simplifies VLAN configuration by allowing VLAN information to be propagated throughout the network. Switches can be configured as VTP servers, clients, or transparent devices, each with specific roles in managing VLANs.

6. How do you troubleshoot VLAN issues on a switch?

To troubleshoot VLAN issues, follow these steps:

1. Verify VLAN configuration using show vlan brief and ensure that VLANs are correctly created and assigned to ports.
2. Check trunking status with show interfaces trunk to ensure that trunk ports are properly configured and that VLANs are being passed.
3. Confirm that switch ports are assigned to the correct VLANs using show interfaces switchport.
4. Use ping and traceroute to test connectivity between devices on different VLANs and ensure that routing is correctly configured if necessary.

7. What is the difference between access ports and trunk ports?

Access ports are used to connect devices to a switch within a single VLAN, while trunk ports are used to connect switches and carry traffic for multiple VLANs. Access ports do not tag VLAN information in the Ethernet frame, whereas trunk ports add VLAN tags to the frames to distinguish between VLANs.

8. How do you configure a switch port as an access port?

To configure a switch port as an access port, follow these steps:

1. Enter global configuration mode by typing configure terminal.
2. Access the specific interface by typing interface [INTERFACE_ID], where [INTERFACE_ID] is the port you want to configure.
3. Set the port mode to access by typing switchport mode access.
4. Assign the port to a VLAN by typing switchport access vlan [VLAN_ID], where [VLAN_ID] is the VLAN number.
5. Exit configuration mode by typing end and save the configuration with write memory or copy running-config startup-config.

9. What command would you use to show the status of all interfaces on a Cisco switch?

To display the status of all interfaces on a Cisco switch, use the show interfaces status command. This command provides information about each interface's status, VLAN assignment, and type.

10. How do you configure a switch to use Rapid Spanning Tree Protocol (RSTP)?

To configure a switch to use Rapid Spanning Tree Protocol (RSTP), follow these steps:

1. Enter global configuration mode by typing configure terminal.
2. Enable RSTP by typing spanning-tree mode rapid-pvst.
3. Exit configuration mode by typing end and save the configuration with write memory or copy running-config startup-config.

11. What is the purpose of the switchport trunk encapsulation dot1q command?

The switchport trunk encapsulation dot1q command is used to specify the trunking encapsulation type on a switch port. IEEE 802.1Q (dot1q) is a common trunking protocol used to carry multiple VLANs across a trunk link by tagging Ethernet frames with VLAN information.

12. How do you configure Inter-VLAN Routing on a Cisco switch?

Inter-VLAN Routing allows communication between different VLANs. To configure Inter-VLAN Routing:

1. Create a VLAN interface for each VLAN by entering global configuration mode and typing interface vlan [VLAN_ID].
2. Assign an IP address to each VLAN interface using ip address [IP_ADDRESS] [SUBNET_MASK].
3. Enable the interface by typing no shutdown.
4. Ensure that the switch has routing capabilities and is properly connected to a router or Layer 3 switch to handle routing between VLANs.

13. What is the function of the port security feature on a switch?

Port security is a feature that allows administrators to control access to switch ports by limiting the number of MAC addresses that can be learned on a port. It helps enhance network security by preventing unauthorized devices from connecting to the network. You can configure port security by setting parameters such as maximum MAC addresses, violation actions (e.g., shutdown, restrict, or protect), and defining secure MAC addresses.

14. How do you configure port security on a Cisco switch?

To configure port security:

1. Enter global configuration mode by typing configure terminal.
2. Access the specific interface by typing interface [INTERFACE_ID].
3. Enable port security by typing switchport port-security.
4. Set the maximum number of MAC addresses by typing switchport port-security maximum [NUMBER].
5. Specify the violation mode by typing switchport port-security violation [MODE], where [MODE] can be shutdown, restrict, or protect.
6. Optionally, specify static MAC addresses by typing switchport port-security mac-address [MAC_ADDRESS].
7. Exit configuration mode by typing end and save the configuration with write memory or copy running-config startup-config.

15. How do you verify port security settings on a switch?

To verify port security settings, use the show port-security command. This command displays information about port security configuration, including the status of secure MAC addresses, the number of security violations, and the configuration of each interface.

16. What is the difference between Static and Dynamic VLANs?

Static VLANs are manually configured by assigning switch ports to a specific VLAN. Dynamic VLANs, on the other hand, use VLAN Membership Policy Server (VMPS) to assign VLANs based on the MAC address of the device connected to the port. Static VLANs provide more control and simplicity, while dynamic VLANs offer more flexibility and scalability in large networks.

Conclusion

Understanding switch configuration is crucial for success in the CCNA exam and in real-world network management. By mastering VLANs, trunking, and troubleshooting techniques, you will be well-equipped to handle the challenges of managing network switches. This article provides a solid foundation of common interview questions and answers on switch configuration, helping you to prepare thoroughly and confidently for your CCNA interview.