Summary
An understanding of the following key points should have been achieved:
  • IP is a best-effort delivery method that uses ICMP messages to alert the sender that the data did not reach its destination.
  • ICMP echo request and echo reply messages allow the network administrator to test IP connectivity to aid in the troubleshooting process.
  • ICMP messages are transmitted using the IP protocol so their delivery is unreliable.
  • ICMP packets have their own special header information starting with a type field and a code field.
  • Identify potential causes of specific ICMP error messages
  • The functions of ICMP control messages
  • ICMP redirect/change request messages
  • ICMP clock synchronization and transit time estimation messages
  • ICMP information request and reply messages
  • ICMP address mask request and reply messages
  • ICMP router discovery message
  • ICMP router solicitation message
  • ICMP congestion and flow control messages