Traffic to Prefilter
Prefiltering is the first phase of access control, before the system performs more resource-intensive evaluation. Prefiltering is simple, fast, and early compared to subsequent evaluation, which uses inner headers and has more robust inspection capabilities.
Based on your security needs and traffic profile, you should consider prefiltering and therefore excluding from any policy and inspection the following:
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Common intraoffice applications such as Microsoft Outlook 365
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Internal DNS traffic
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Elephant flows, such as server backups