An engineer is implementing Cisco CES in an existing Microsoft Office 365 environment and must...

To route inbound email to Cisco Cloud Email Security (CES), the engineer must modify the MX record of the domain to point to the CES hostname or IP address. The MX record is a DNS record that specifies the mail server responsible for accepting email messages on behalf of a domain name. By changing the MX record, the engineer can direct all incoming email traffic to the CES gateway, where it can be filtered and scanned for threats before being delivered to the Microsoft Office 365 mailboxes. The other options are not relevant for this task. A CNAME record is a DNS record that maps an alias name to a canonical name. An SPF record is a DNS record that identifies the authorized senders of email for a domain. A DKIM record is a DNS record that contains a public key for verifying the digital signature of email messages sent from a domain. References :=

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Configure Microsoft 365 with Secure Email

Configure Microsoft 365 with Secure Email - More

[Cisco Cloud Email Security - Configuration Guide]