When you are troubleshooting duplex mismatches, which two errors are typically seen on the fullduplex end? (Choose two.)
A.
runts
B.
FCS errors
C.
interface resets
D.
late collisions
Explanation:
FCS, or File Check Sequence Errors, are one of the more common errors found in a network.
When packets are transmitted and received, each contains a File Check Sequence that allows the
receiving device to determine if the packet is complete without having to examine each bit. This is
a type of CRC, or Cyclical Redundancy Check. Barring a station powering up or down during a
transmission, the most common cause of these errors is noise. Network noise can be caused by
cabling being located too close to noise sources such as lights, heavy machinery, etc. If a cabling
installation is particularly faulty — such as pairs being untwisted, improper terminations, field
terminated patch cables, etc. — these errors will occur on your network. Poorly manufactured
components or minimally compliant components that are improperly installed can compound this
issue. Cabling segments that are too long can also cause these errors.
Cabling issues, as defined above, or MAC layer packet formation issues (possibly hardware
related) cause these errors. A faulty LAN driver can also cause this. Replacement of the driver will
correct the latter issue. These errors can also be seen in correlation with RUNT packets or
packets that are too short. Noise, however, is the most common cause and can generally be
corrected by addressing the cabling channel.