A vulnerability assessment report has been submitted to a client.

 The discovery phase of a vulnerability assessment is the process of identifying and enumerating the hosts, services, and applications that are in scope of the assessment. This phase involves techniques such as network scanning, port scanning, service scanning, and banner grabbing. If one third of the hosts that were in scope are missing from the report, it means that the discovery phase was not performed properly or completely, and some hosts were not detected or included in the assessment. The enumeration, reporting, and detection phases are not likely to cause this error, as they depend on the results of the discovery phase. References: CISSP All-in-One Exam Guide, Eighth Edition, Chapter 7: Security Assessment and Testing, page 857; Official (ISC)2 Guide to the CISSP CBK, Fifth Edition, Chapter 6: Security Assessment and Testing, page 794.