Successful backup job without a verified restore chain

A fictional database service reports successful nightly base backups and frequent log backups. The recovery requirement names a particular point during the afternoon. During a written recovery review, the supplied inventory shows that one required log segment is missing and that the relevant encryption key has not been made available to the authorized recovery process. A colleague proposes promising the exact target point because every nightly job is green. Another proposes preserving the available chain, checking actual consistency requirements and testing the reachable recovery points. This exercise authorizes no restore or production operation. It asks the learner to distinguish backup completion from a complete usable chain and to communicate the unresolved recovery limitation honestly.