Exam N10-008 topic 1 question 59 discussion

If duplex and RX/TX are correct, then late collisions most likely occur from cable lengths being too excessive.

Long cables cause CRC issues, not collisions. Half duplex shouldn't have collisions. This can only mean bad NIC. Hardware issue. Source: network engineer.

The most likely cause of late collisions on a half-duplex link, even when both devices are configured for half duplex, is: C. The cable length is excessive Late collisions typically occur when the cable length exceeds the maximum allowed for Ethernet standards, causing the collision detection mechanism to fail12. This results in collisions being detected too late in the transmission process.

Late collisions on a half-duplex link indicate that a collision occurred after the normal time frame for collision detection has passed. In a properly functioning network, late collisions on a half-duplex link are typically caused by: C. The cable length is excessive Late collisions can occur due to the time it takes for the electrical signal to propagate along the length of the cable. When the cable length is excessive, the electrical signal may not reach the other end of the cable before a collision occurs, resulting in late collisions. Therefore, an excessive cable length is the most likely cause of late collisions on a half-duplex link when both devices are correctly configured for half duplex.

The keyword here is late collisions, only cable being too long will create a late collisions problem.

The answer is C. A is not because there are late collisions, so it was properly terminated. B isn't the answer either because the question says "The engineer verifies that the devices on both ends of the connection are configured for half duplex". D isn't the answer either because a hardware issue or NIC would not allow a transmission at all. So the only answer is C because late collisions happen due to exceeded cable length limits.

The answer is C. A is not because there are late collisions, so it was properly terminated. B isn't the answer either because the question says "The engineer verifies that the devices on both ends of the connection are configured for half duplex". D isn't the answer either because a hardware issue or NIC would not allow a transmission at all. So the only answer is C because late collisions happen due to exceeded cable length limits.

Answer is C: Late collisions on a half-duplex link are typically caused by a mismatch in the configuration of the devices involved. In this scenario, where both ends of the connection are configured for half duplex, the most likely cause of late collisions is a problem with the cable infrastructure. To address this issue, you may want to check and ensure that the cable length is within the specified limits for the network technology in use.

Late collision: when a collision is detected outside of the standard collision window. This indicates that the collision happened after a significant portion of the frame was transmitted. So only part of the frame made it. ChatGPT says it's D. NIC.

Excessive cable length can lead to late collisions in a half-duplex Ethernet connection. Late collisions occur when a device detects that a collision has occurred after it has already transmitted a significant portion of its frame. This can happen because it takes time for the electrical signal to propagate down a cable, and if the cable is too long, the signal may not reach the other end in time to detect the collision.

This is a bad question, again. This could be caused by either the cable length being too long, or a hardware (NIC) issues. As to which is more likely? IDK. Is it more likely whoever installed the thing used slgihtly too much cable and you only noticed now? Or is it more likely that this (probably legacy) system had a hardware failure. I guess I would still pick the cable answer for the simple fact that if the nic card was bad, you probably wouldnt have much of a connection at all. Hate it, but thats all I got

When I put this exact question into ChatGPT, I got only 1 answer: "If an engineer notices late collisions on a half-duplex link and has verified that the devices on both ends of the connection are configured for half duplex, the MOST likely cause of this issue is: Excessive Cable Length: Late collisions in a half-duplex environment are often caused by signals taking too long to propagate along the cable. In a half-duplex setup, the devices can either transmit or receive at any given time, but not both simultaneously. If the cable length exceeds the maximum allowed for the specific Ethernet standard being used (e.g., Ethernet, Fast Ethernet), it can lead to signal propagation delays, resulting in collisions occurring even after a portion of the frame has been transmitted. To address this issue, the engineer should check the cable length and make sure it adheres to the recommended limits for the specific Ethernet standard. If the cable length is too long, it may need to be shortened or replaced with a higher-quality cable to reduce signal propagation delays and prevent late collisions." Thus, ChatGPT selects "C. The cable length is excessive"

ChatGPT says: Late collisions on a half-duplex link can occur when a device transmits data while another device is still transmitting on the same link. In this scenario, since the devices on both ends of the link are configured for half-duplex, they cannot receive data while transmitting, which can result in late collisions. Therefore, the most likely cause of this issue is B. One of the devices is misconfigured. It is possible that one of the devices is operating in full-duplex mode instead of half-duplex mode. In full-duplex mode, devices can transmit and receive data at the same time, which eliminates the possibility of collisions. However, if one device is configured for full-duplex mode and the other device is configured for half-duplex mode, it can result in collisions and other performance issues. Other potential causes, such as improper termination, excessive cable length, or a hardware issue, are less likely to cause late collisions on a half-duplex link.

when i think of C, the cable length may be 100km+, it seems impossible I go for D

B. The cable length is excessive is the most likely cause of this issue. Late collisions occur when a device tries to transmit a frame onto the network, but detects a collision has occurred after it has finished transmitting the frame. In half-duplex mode, collisions can occur because both devices are trying to transmit on the same link at the same time. Excessive cable length can cause a delay in the signal reaching the other end of the cable, which can result in collisions. The longer the cable, the longer the delay, and the higher the chances of a collision occurring. Improperly terminated links or hardware issues can also cause collisions, but they are less likely to be the cause in this scenario where both devices are configured for half duplex.

One of the devices certainly have an hardware issues and could not sense when the media is engage, hence sending at same time leading to collision. If Network card is functional without fault, it should sense the transmission and hold for clearance.

The most likely cause of the late collisions on a half-duplex link is that the cable length is excessive. In half-duplex mode, when two devices send data at the same time, a collision occurs, and both devices must wait for a random period before retransmitting the data. If the cable length is excessive, it may take longer for the collision signal to reach the far end of the cable, causing late collisions. To resolve the issue, the engineer should reduce the cable length or switch to full-duplex mode.