The statement describing commit confirmed 5 is correct. In Junos OS, configuration changes are first made to a candidate configuration . They do not become the active operational configuration merely because they have been entered in configuration mode. A commit operation is required to validate and activate those changes.
The commit confirmed mechanism provides an important administrative safety feature. When the administrator enters:
commit confirmed 5
Junos OS activates the candidate configuration but requires confirmation within 5 minutes . If the configuration is not confirmed before the timer expires, Junos OS automatically rolls back to the previously committed configuration. Juniper explicitly documents that the optional number following commit confirmed specifies the confirmation period in minutes.
Option A is incorrect because operational mode is primarily used for monitoring, troubleshooting, maintenance, and operational commands rather than making persistent configuration changes. Option B is incorrect because configuration-mode edits remain candidate changes until committed. Option D is also incorrect: rollback 0 does not restore factory defaults . It loads the most recently committed configuration and effectively removes pending uncommitted modifications.
Study Guide Reference Topics: Configuration Basics - candidate versus active configuration, commit operations, confirmed commits, configuration rollback, and Junos CLI modes.