CAS-005 · Question #172
A security engineer added a new server to the company email cluster. The server has a new external IP address associated with it. After a few days, the service desk started receiving complaints from…
The correct answer is D. SPF F. PTR. To prevent outgoing emails from being flagged as spam after adding a new email server, the security engineer must update the SPF record to authorize the new server's IP and the PTR record for proper reverse DNS resolution.
Question
A security engineer added a new server to the company email cluster. The server has a new external IP address associated with it. After a few days, the service desk started receiving complaints from users about their outgoing messages to customers being flagged as spam. Which of the following records should the security engineer update to fix the issue? (Choose two.)
Options
- ADMARC
- BCNAME
- CMX
- DSPF
- EMIME
- FPTR
How the community answered
(30 responses)- B10% (3)
- C3% (1)
- D73% (22)
- E13% (4)
Why each option
To prevent outgoing emails from being flagged as spam after adding a new email server, the security engineer must update the SPF record to authorize the new server's IP and the PTR record for proper reverse DNS resolution.
While DMARC relies on SPF, updating SPF is the direct action needed here; DMARC itself is a policy and reporting mechanism that will eventually reflect the SPF changes but isn't the primary record to update for the new server's sending authorization.
CNAME records are used for aliasing hostnames and are not directly involved in outgoing email server authentication or reverse DNS lookups.
MX (Mail Exchanger) records specify which servers receive email for a domain, not which servers are authorized to send outgoing email.
The SPF (Sender Policy Framework) record must be updated to include the new external IP address of the email server, authorizing it to send mail on behalf of the domain and preventing recipient mail servers from flagging messages as spam.
MIME (Multipurpose Internet Mail Extensions) defines how email content types are handled, not email server authentication or IP address authorization.
The PTR (Pointer) record, also known as a reverse DNS record, should be configured for the new external IP address to map it back to the email server's hostname, as many recipient mail servers perform reverse DNS lookups to verify sender legitimacy.
Concept tested: Email deliverability DNS records (SPF, PTR)
Source: https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/email-authentication-spf-overview?view=o365-worldwide
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