NIST-AC-7(4) Use of Alternate Authentication Factor

(a) Allow the use of [Assignment: authentication factors] that are different from the primary authentication factors after the number of organization-defined consecutive invalid logon attempts have been exceeded; and (b) Enforce a limit of [Assignment: number] consecutive invalid logon attempts through use of the alternative factors by a user during a [Assignment: time period].

The use of alternate authentication factors supports the objective of availability and allows a user who has inadvertently been locked out to use additional authentication factors to bypass the lockout.