CompTIA Server+ (SK0-005)TroubleshootingMedium
A Linux server is experiencing extremely slow file transfers over its network connection. Running `ifconfig` shows the interface is up, and `ping` to the gateway is successful. However, `ethtool eth0` (assuming `eth0` is the interface) shows 'Speed: 100Mb/s' and 'Duplex: half', even though the switch port it's connected to is configured for 1Gb/s full-duplex. What is the MOST likely cause of the slow transfers?
- AHigh CPU utilization on the server.
- BA faulty NIC on the server.
- CA duplex mismatch between the server and the switch.
- DA misconfigured MTU size on the server.
Show answer & explanationAnswer & explanation
Correct answer: C. A duplex mismatch between the server and the switch.
A duplex mismatch, where one side is configured for full-duplex and the other for half-duplex, causes severe performance degradation due to collision detection mechanisms. The `ethtool` output clearly shows the server is operating at half-duplex while the switch port is configured for full-duplex, indicating a classic duplex mismatch.
Why the other options are wrong
- A. High CPU utilization would be visible in `top` or `htop` and would impact overall server performance, not specifically force a network interface to 100Mb/s half-duplex.
- B. A faulty NIC could cause various issues, but the specific '100Mb/s half-duplex' configuration points more directly to a negotiation issue rather than a complete hardware failure.
- D. An MTU mismatch usually causes packet fragmentation or dropped packets, not necessarily a reduction to 100Mb/s half-duplex.
Duplex Mismatch
Occurs when two connected network devices are configured with different duplex settings (e.g., one full-duplex, one half-duplex), leading to severe performance issues due to excessive collisions.
- Causes significant network performance degradation.
- Often results in high collision rates on half-duplex side.
- Can be identified by checking link speed and duplex settings on both ends.
Memory trick: If speed's slow and duplex is off, your network's trying to cough.