TCP port 23 – Time-to-live exceeded
A. The scan on port 23 was able to make a connection to the destination host prompting the firewall to respond with a TTL error
B. The lack of response from ports 21 and 22 indicate that those services are not running on the destination server
C. The scan on port 23 passed through the filtering device. This indicates that port 23 was not blocked at the firewall
D. The firewall itself is blocking ports 21 through 23 and a service is listening on port 23 of the target host
Answer:C
TCP port 23 – Time-to-live exceeded
A. The scan on port 23 was able to make a connection to the destination host prompting the firewall to respond with a TTL error B. The lack of response from ports 21 and 22 indicate that those services are not running on the destination server C. The scan on port 23 passed through the filtering device. This indicates that port 23 was not blocked at the firewall D. The firewall itself is blocking ports 21 through 23 and a service is listening on port 23 of the target host