AC.2.009 Limit unsuccessful logon attempts.

CMMC Practice AC.2.009: Limit unsuccessful logon attempts.

Links to Publicly Available Resources

CMMC CLARIFICATION (Ref CMMC – Appendix B)
Consecutive, unsuccessful logon attempts may indicate malicious activity. You can mitigate these types of attacks by limiting the number of unsuccessful logon attempts. There are many ways to do this. Having three consecutive, unsuccessful logon attempts is a common setting. Organizations should set this number at a level that fits their risk profile. Fewer unsuccessful attempts provide higher security.
After the system locks an account, it has several options to unlock it. The most common is to keep the account locked for a predefined time. After that time, the account unlocks. Another option is to keep the account locked until an administrator unlocks it.