200-301 Question 161
Select 3A network engineer is troubleshooting connectivity issues between devices on a switch. They notice that the MAC address table of the switch is not updating correctly. Which of the following could be potential causes of this issue?
- A
A device connected to the switch is constantly sending frames with a static source MAC address.
- B
The switch has reached its MAC address table capacity limit.
- C
The switch is operating in store-and-forward mode, causing delays in processing MAC addresses.
- D
The switchport where the device is connected is configured as an access port.
- E
There is a Layer 2 loop in the network, causing excessive flooding of frames.
Show answer and explanation
Correct answers: A, B, E
Explanation
The MAC address table is vital for efficient Layer 2 switching. Issues like static MAC addresses, table capacity limits, and network loops can disrupt its functionality, leading to connectivity problems. Understanding these scenarios helps in diagnosing and resolving MAC address table-related issues effectively.
- A. Correct.
A device constantly sending frames with a static source MAC address can cause the switch to overwrite or fail to update the MAC address table correctly.
- B. Correct.
If the switch's MAC address table has reached its capacity, it will fail to learn new MAC addresses, causing connectivity and forwarding issues.
- C. Incorrect.
The store-and-forward mode affects frame forwarding performance but does not directly impact the MAC address table updates.
- D. Incorrect.
Configuring a switchport as an access port does not prevent the MAC address table from learning addresses; it only defines VLAN membership for the port.
- E. Correct.
A Layer 2 loop results in excessive flooding of frames, which can overwhelm the switch and cause instability in the MAC address table.