Which statement about ICMP is true?

• A. ICMP is a transport layer protocol.
• B. ICMP is used to perform reliable data transfer.
• C. ICMP helps diagnose network issues by reporting errors.
• D. ICMP replaces TCP in the handshake.

Answer: (C)

ICMP operates at the network layer and is designed to report errors and help diagnose connectivity issues rather than transfer data. When a router or host can’t deliver a packet, it may send back an ICMP message with information such as Destination Unreachable or Time Exceeded. Tools like ping and traceroute rely on ICMP's echo messages and diagnostic reports to determine reachability and path issues. Because ICMP is not a transport protocol, it does not provide reliable data transfer, and it doesn’t participate in the TCP handshake. Those other statements describe functions that TCP or a transport protocol handles, not ICMP. So the statement about ICMP helping diagnose network issues by reporting errors is the accurate description.