Instruction Manual

Module 8 Summary

Before students begin Module 9, they should know where to look for many of the error

messages they may encounter.

Online assessment options include the end-of-module online quiz in the curriculum and the

online Module 8 exam. This is a very descriptive module so vocabulary or scenario-based

quizzes may be the preferred form of assessment.

Students should understand the following main points:

• 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 with the IP protocol so their delivery is unreliable.

• ICMP packets have their own special header information, which starts with a type

field and a code field.

• 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