Address Resolution Protocol (ARP)

Correct Answer: arp -a

The 'arp -a' command is used to display the ARP (Address Resolution Protocol) cache, which maps IP addresses to MAC addresses. Using this command, the technician will be able to verify whether there is a correct match between the IP addresses and MAC addresses of the two hosts which are having connectivity issues. If there are incorrect or no entries for the hosts in the ARP cache, this can suggest that an ARP issue is causing the connectivity problems. The other commands do not directly address the ARP issue. 'ipconfig /all' displays all the current TCP/IP network configurations and is generally used for troubleshooting network connectivity, but it does not specifically address the ARP issue. 'netstat -r' displays the routing table, and 'ping -t' sends a constant ping command to a specified address, neither of which are directly related to resolving an ARP issue.

Correct Answer: Implement ARP inspection on the switch.

The best approach to mitigate the issue of a switch flooded with broadcast frames causing high CPU utilization is to 'Implement ARP inspection on the switch'. This technique will help to validate incoming ARP requests and responses thus preventing excessive broadcast frames. Answer 'Upgrade the switch firmware' might not directly address the problem at hand. While it can improve overall system performance, it does not specifically deal with excessive broadcast frames. Answer 'Disable the affected port' may momentarily cease the issues but doesn't effectively resolve the broadcast problem. Instead, it risks adding more downtime. Answer 'Remove the switch from the network' is neither a practical nor an effective solution to this specific problem as it could impact the entire network communication.

Correct Answer: Enable Dynamic ARP Inspection.

In this case, the best solution is to 'Enable Dynamic ARP Inspection'. Dynamic ARP inspection is a security feature that validates ARP packets in a network. It ensures that only valid ARP requests and responses are relayed. Dynamic ARP Inspection prevents so called 'man-in-the-middle attacks'. This form of attack can permit an attacker to intercept, alter or even stop data to and from a target device. Enabling Dynamic ARP Inspection would prevent unauthorized Address Resolution Protocol (ARP) entries as it dynamically binds the IP addresses to MAC addresses. 'Configure a firewall rule' could be helpful but should be applied in coherence with other methods, as it cannot prevent unauthorized ARP entries by itself. 'Enable Private VLANs' only segregates Layer 2 traffic and has no effect on ARP spoofing. Meanwhile, 'Disable IPV6' won't affect the ARP that works in IPV4 networks, so it is also not a correct answer.