This Counter32 object counts packets received by a port that are between 64 and 1522 bytes but have a bad FCS along with a non-integral number of bytes, indicating an alignment error. An admin troubleshooting physical-layer problems on a link watches this counter for growth, since alignment errors typically point to a duplex mismatch or cabling fault rather than a software issue. For example, a port showing rising alignment errors right after a duplex setting was changed would lead the admin to suspect a duplex mismatch with the connected device.