Day 9 - Switch Interfaces (Commands)

Question 1

A network engineer needs to manually configure the interface GigabitEthernet0/1 on a switch to connect to a router. The company policy requires manually setting the speed to 1000 Mbps and the duplex to full. Starting from the SW1(config)# prompt, which command sequence correctly accomplishes this?

A) interface g0/1 → speed 1000 → duplex full
B) interface g0/1 → speed auto → duplex auto
C) interface g0/1 → duplex full → shutdown → speed 1000
D) enable → interface g0/1 → speed 1000 → duplex full

Answer 1

✅ A) interface g0/1 → speed 1000 → duplex full
→ Correct. This sequence correctly selects the interface from global configuration mode and then applies the appropriate commands to manually set the speed and duplex settings.

B) interface g0/1 → speed auto → duplex auto
→ Incorrect. The task is to manually configure the settings. Using the auto keyword would re-enable auto-negotiation, which is the opposite of the required task.

C) interface g0/1 → duplex full → shutdown → speed 1000
→ Incorrect. While the duplex and speed commands are correct, there is no requirement to shut down the interface to apply these settings.

D) enable → interface g0/1 → speed 1000 → duplex full
→ Incorrect. The enable command is used to enter privileged EXEC mode from user EXEC mode. The prompt SW1(config)# indicates the user is already past that stage and is in global configuration mode.

Question 2

Why would a network engineer choose to manually configure the speed and duplex settings on an interface connecting two network devices (like a switch and a router), rather than allowing the devices to negotiate these settings automatically?

A) To improve security by preventing unauthorized devices from connecting.
B) To ensure a stable and reliable link by preventing an auto-negotiation failure or mismatch, which can lead to performance issues like collisions and errors.
C) To force the interface to operate at a slower speed to conserve power.
D) To enable the interface to carry traffic for multiple VLANs.

Answer 2

A) To improve security by preventing unauthorized devices from connecting.
→ Incorrect. Speed and duplex settings do not provide security against unauthorized access. Features like port security are used for that purpose.

✅ B) To ensure a stable and reliable link by preventing an auto-negotiation failure or mismatch, which can lead to performance issues like collisions and errors.
→ Correct. While auto-negotiation usually works well, it can sometimes fail, especially between devices from different vendors. A common failure results in one side being full-duplex and the other half-duplex, causing massive performance degradation. Manually setting both sides to match is a common troubleshooting step and a best practice in critical infrastructure links.

C) To force the interface to operate at a slower speed to conserve power.
→ Incorrect. The goal is typically to ensure the link operates at its maximum possible speed. While you could use this to slow down a link, that is not the primary reason for manual configuration.

D) To enable the interface to carry traffic for multiple VLANs.
→ Incorrect. Carrying multiple VLANs is the function of a trunk port, which is configured with the switchport mode trunk command, not the speed or duplex commands.

Question 3

An administrator has configured a description on router R1’s GigabitEthernet0/0 interface. They run the show ip interface brief command to verify their work but notice the description is not displayed in the output. Which command should they have used to see the full interface details, including the description?

A) show running-config
B) show cdp neighbors detail
C) show interfaces description
D) show interfaces

Answer 3

A) show running-config
→ Incorrect. While this command would show the description, it’s not the primary command for checking the status and details of interfaces. It shows the entire device configuration.

B) show cdp neighbors detail
→ Incorrect. This command shows information about directly connected Cisco devices, but it does not display the locally configured interface description.

C) show interfaces description
→ Incorrect. While this command exists on some platforms, a more common and comprehensive command provides this information and more. The show interfaces description command often only shows the description and status, not other important details.

✅ D) showow interfac
→ Correct. This is the standard command to view detailed information about all interfaces, including their status, protocol, hardware details, traffic statistics, and thees

Question 4

An administrator is working on switch SW1 and has configured descriptions on all the access ports. They want to see a single, clean, table-based output that lists each port, its description, its status (connected/notconnect), and its assigned VLAN. Which command is best suited for this specific task on a switch?

A) show interfaces
B) show ip interface brief
C) show interfaces status
D) show vlan brief

Answer 4

A) show interfaces
→ Incorrect. While this command works on a switch, it provides a very long and detailed output for each port, which is not the concise, table-based view requested.

B) show ip interface brief
→ Incorrect. This is the primary summary command for a router. On a switch, it’s less useful as it doesn’t show crucial Layer 2 information like the description or VLAN.

✅ C) show interfaces status
→ Correct. This command is designed specifically for switches to provide a clean, one-line-per-port table that includes the description, status, VLAN, duplex, and speed, matching the request perfectly.

D) show vlan brief
→ Incorrect. This command is excellent for seeing which ports are in which VLAN, but it does not display the interface description.

Question 5

An administrator needs to disable a contiguous range of unused access ports on a switch, from FastEthernet0/10 to FastEthernet0/24, as a security best practice. Starting from global configuration mode SW1(config)#, which is the most efficient and correct command sequence to accomplish this?

A) interface range f0/10-24 → no shutdown
B) interface f0/10-24 → shutdown
C) interface range f0/10-24 → shutdown
D) no interface range f0/10-24

Answer 5

A) interface range f0/10-24 → no shutdown
→ Incorrect. The no shutdown command is used to enable an interface, which is the opposite of the desired action.

B) interface f0/10-24 → shutdown
→ Incorrect. This sequence is missing the range keyword, which is required to select multiple interfaces at once. The command would fail.

✅ C) interface range f0/10-24 → shutdown
→ Correct. This is the most efficient method. The interface range command selects all the specified ports, and the shutdown command then disables all of them simultaneously.

D) no interface range f0/10-24
→ Incorrect. The no prefix is used to remove a configuration, not to disable the interfaces themselves. This is not a valid command.

Question 6

After running the shutdown command on a range of switch ports, an administrator wants to verify that the ports are now disabled. Which command provides the clearest, single-line output for each port, showing a “Status” of disabled?

A) show ip interface brief
B) show running-config
C) show interfaces status
D) show vlan brief

Answer 6

A) show ip interface brief
→ Incorrect. This command is primarily used on routers and does not provide the specific disabled status for Layer 2 switch ports in its output.

B) show running-config
→ Incorrect. While the shutdown command would appear under each interface in the running configuration, this is not a clear or efficient way to check the live operational status of many ports at once.

✅ C) show interfaces status
→ Correct. This is the ideal command for this task on a switch. It provides a clean, table-based view with a dedicated “Status” column that will explicitly show disabled for any port that has been shut down.

D) show vlan brief
→ Incorrect. This command shows VLAN assignments

Question 7

You have just configured several access ports on SW1 with descriptions and assigned them to various VLANs. Which single command provides the most efficient, table-based view of each port’s description, status, duplex, speed, and assigned VLAN?

A) show interfaces
B) show vlan brief
C) show ip interface brief
D) show interfaces status

Answer 7

A) show interfaces
→ Incorrect. This command provides an extremely detailed, multi-page output for each port, which is not an efficient summary.

B) show vlan brief
→ Incorrect. This command is excellent for seeing which ports are in which VLAN, but it does not show the interface description, status, or speed/duplex settings.

C) show ip interface brief
→ Incorrect. This command is the primary summary tool for routers to check IP addresses. It is not ideal for checking Layer 2 details on a switch.

✅ D) show interfaces status
→ Correct. This is the perfect command for this task on a switch, providing a clean, one-line summary of all the key Layer 2 information requested.

Question 8

You are troubleshooting a connectivity issue and need to check the IP address and line protocol status of all interfaces on router R1. Which command provides the quickest and most concise summary for this specific Layer 3 information?

A) show interfaces
B) show ip interface brief
C) show protocols
D) show running-config

Answer 8

A) show interfaces
→ Incorrect. This provides far too much detail when all you need is a quick summary of IP addresses and status.

✅ B) show ip interface brief
→ Correct. This is the standard, go-to command for viewing a concise table of Layer 3 interface information (IP address and status) on a router.

C) show protocols
→ Incorrect. This command shows the status of configured routed protocols like OSPF or EIGRP, not the status of the interfaces themselves.

D) show running-config
→ Incorrect. This shows the saved configuration commands but does not show the live operational status of the interfaces