A port scan returns a ‘closed’ response. What does this mean?

ITExam Editorial Team Last Updated: May 10, 2026

IT Exam Items Repository › Category: Introduction to Cybersecurity › A port scan returns a ‘closed’ response. What does this mean?

A port scan returns a ‘closed’ response. What does this mean?

There was no reply from the host
A service is listening on the port
Connections to the port will be denied

Explanation: A ‘closed’ response (which the sources also group with ‘denied’ or ‘not listening’) indicates that the specific port or service is not running on the target computer. Because the service is not active, any attempt to connect to that port is rejected, and the port cannot be exploited by an attacker.

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