Description: The number of invalid CA messages received from this DCS. During Master/Slave negotiation state, two types of messages are correct: 1) CA from the DCS has the M, I, and O bits on, with no CSAS records and sender's ID is larger than the LSID. 2) CA from the DCS has the M and I bits off and the sender's ID is smaller than the LSID. All other types of CA messages are invalid and ignored. During Cache Summarize State, two kinds of message errors are possible: 1) M bit in received CA is set incorrectly; 2) CA sequence number is neither equal nor one more than the current LS's CA sequence number when LS is slave or CA sequence number is neither equal nor one less than the current LS's CA sequence number when LS is master. Other common errors include failed check sum, failed authentication if applicable, errors in the message fields.