Examine the Data Guard configuration: DGMGRL> show configuration; Configuration - Animals Protection Mode: MaxPerformance Databases: dogs- Primary…

The ORA-16627 error indicates that no standby database in the configuration meets the requirements for the requested protection mode, which is Maximum Protection. Maximum Protection mode requires at least one participating standby database to use synchronous (SYNC) redo transport. The configuration has two standbys: cats and sheep. The cats database is a snapshot standby, which is open read-write and does not receive redo from the primary, thus it cannot support Maximum Protection. Therefore, the failure must be due to the sheep database also not meeting the requirements. The most common reason for this is that its redo transport mode is set to asynchronous (ASYNC) instead of SYNC.

B: The redo transport mode for cats is irrelevant because as a snapshot standby, it is ineligible to support Maximum Protection regardless of its transport settings. C: While the transport mode for sheep must be ASYNC, we cannot conclude anything about the transport mode for cats, as it is disqualified for other reasons. D: The statement that Cats is a snapshot standby is true, as shown in the configuration. However, this is a given fact, not the conclusion drawn from the ORA-16627 error message.

Oracle Database Data Guard Concepts and Administration, 19c, Chapter 5, "Data Guard Protection Modes". This chapter states, "For maximum protection mode, at least one standby database must be configured to use the SYNC transport mode."

Oracle Database Error Messages, Documentation for ORA-16627. The cause is listed as: "The operation is not allowed because no standby database in the configuration satisfies the requirements of the specified protection mode."