Hi @Sathishkumar Singh ,
now we would like to know what is the best practice to use for Exchange Servers *.Wildcard or Single domain of each applications?
From the perspective of Exchange severs, the best practice is to use as few certificates as possible, which usually means using SAN certificates or wildcard certificates.
More information, hopefully you can find the article below helpful:
Digital certificates and encryption in Exchange Server-Digital certificates and encryption in Exchange Server
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