CompTIA Network+ Question B-86

A network technician is performing a tracert command to troubleshoot a website-related issue. The following output is received for each hop in the tracert:
1 * * * Request timed out.
2 * * * Request timed out.
3 * * * Request timed out.
The technician would like to see the results of the tracert command. Which of the following will allow the technician to perform tracert on external sites but not allow outsiders to discover information from inside the network?

A. Enable split horizon to allow internal tracert commands to pass through the firewall
B. Enable IGMP messages out and block IGMP messages into the network
C. Configure the firewall to allow echo reply in and echo request out of the network
D. Install a backdoor to access the router to allow tracert messages to pass through

Correct Answer: C

Tracert makes use of ICMP echo packets to trace the route between two hosts. For the command to be successful, the firewall has to allow incoming echo replies and outgoing echo requests.