Now, it's time to check your knowledge. Select the best response, and then check your answers with those in Assessment:

1. ICMP communicates issues that prevent data delivery. Common issues include the network or port being _____.
   1. Stateful
   2. Inspected
   3. Unreachable
   4. ARP enabled
2. Some of the ICMP types are no longer used since, over time, they have been found to be ineffective and are considered _____.
   1. Quenched
   2. Unreachable
   3. Digital
   4. Deprecated
3. In ICMPv6, a _____ message can be sent when there is an issue determining a field value in the IPv6 header or the IPv6 extension header.
   1. Time exceeded
   2. Parameter problems
   3. Packet too big
   4. Source quench

4. When setting firewall rules, the only essential ICMP traffic is type _____. The others are optional.
   1. 3
   2. 1
   3. 8
   4. 2
5. ICMP can be used in a malicious way. One way is a ______ scan that uses a series of ICMP echo request packets on a network to see what hosts are alive and responding.
   1. Payload
   2. Ping
   3. Port
   4. Checksum