Possible Reasons for Interface g0/1 Down/Down State
Question
The SW1 interface g0/1 is in the down/down state. What are two reasons for the interface condition? (Choose two.)
Answers
Explanations
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A. B. C. D. E.CD
The "down/down" state means that both the line protocol and physical layer protocol of the interface are in the down state. This indicates that the interface is not functioning properly.
There are several possible reasons for an interface to be in the down/down state, but two common reasons are:
A. Protocol Mismatch: A protocol mismatch occurs when the two ends of the link are configured with different protocols. For example, if one end of the link is configured for a protocol such as OSPF and the other end is configured for a different protocol such as EIGRP, then the link will not come up. The link will remain in the down/down state until the protocols are configured to match.
B. Duplex Mismatch: A duplex mismatch occurs when the two ends of the link are configured with different duplex settings. For example, if one end of the link is configured for full duplex and the other end is configured for half duplex, then the link will not come up. The link will remain in the down/down state until the duplex settings are configured to match.
C. Interface Shutdown: If the interface is manually shutdown, either by a network administrator or through a software command, the interface will remain in the down/down state until it is brought back up.
D. Interface Error-disabled: If the interface is configured to shut down automatically when certain errors occur, the interface may become error-disabled. In this case, the interface will remain in the down/down state until the error is resolved and the interface is re-enabled.
E. Speed Mismatch: A speed mismatch occurs when the two ends of the link are configured with different speeds. For example, if one end of the link is configured for 100 Mbps and the other end is configured for 1 Gbps, then the link will not come up. The link will remain in the down/down state until the speeds are configured to match.
In summary, the two most common reasons for an interface to be in the down/down state are protocol mismatch and duplex mismatch. However, other factors such as interface shutdown, error-disabled state, and speed mismatch can also cause the interface to be in the down/down state.
