CompTIA Linux+ (XK0-004) — Question 297

A security team informs the Linux administrator that a specific server is acting as an open relay.
To which of the following is the security team referring?

Answer options

• A. The server is running the SSH service and is open to the Internet, allowing outside sources to log into the server without source IP address filtering.
• B. The server is acting as an unmanaged router, open to the Internet, and is allowing outside Internet traffic into the network with no filtering.
• C. The server is acting as a web proxy and allowing outside unauthenticated sources to connect to the server, effectively hiding the source's IP address for malicious activities.
• D. The server has an email service configured to allow outside sources to send email to other external parties on the Internet without validation.

Correct answer: D

Explanation

The correct answer is D because an open relay in email terminology refers to a mail server that permits anyone on the Internet to send emails to external addresses without checking their identity. Options A, B, and C describe different security issues but do not pertain specifically to email relay functionality.