What is the best practice regarding licensing for a backup master to support Master Redundancy in a network without cent

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What is the best practice regarding licensing for a backup master to support Master Redundancy in a network without centralized licensing?

A. Backup master only requires the AP license
B. Supported limits and installed licenses should be the same on primary master and backup Master
C. Licenses are pushed from the primary to the backup Master along with the configuration
D. The Backup Master does not require licenses to support master redundancy
E. On the backup only one license of each type,is needed.