CompTIA Network+ (N10-009) — Question 156

A network engineer performed a migration to a new mail server. The engineer changed the MX record, verified the change was accurate, and confirmed the new mail server was reachable via the IP address in the A record. However, users are not receiving email. Which of the following should the engineer have done to prevent the issue from occurring?

Answer options

• A. Change the email client configuration to match the MX record.
• B. Reduce the TTL record prior to the MX record change.
• C. Perform a DNS zone transfer prior to the MX record change.
• D. Update the NS record to reflect the IP address change.

Correct answer: B

Explanation

The correct answer is B because reducing the TTL (Time to Live) value allows DNS changes, like the MX record update, to propagate more quickly, minimizing downtime. Options A, C, and D do not address the propagation delay issue caused by the original TTL settings, making them ineffective in preventing the problem.