Which protocol is used to send error messages and is commonly used with ping to test connectivity?

Which protocol is used to send error messages and is commonly used with ping to test connectivity?

• A. UDP
• B. TCP
• C. ARP
• D. ICMP

Answer: (D)

ICMP handles control messages like error reporting and network diagnostics. Ping uses ICMP Echo Request and Echo Reply to test reachability: you send an Echo Request, and if the destination can be reached, it replies with an Echo Reply. When there are issues, routers can send ICMP error messages such as Time Exceeded (if a packet’s TTL expires) or Destination Unreachable, which helps identify where connectivity breaks down. UDP and TCP are transport-layer protocols for delivering data—UDP is connectionless and doesn't guarantee delivery, while TCP provides reliable, ordered delivery. ARP maps IP addresses to hardware addresses on a local network and isn’t used for end-to-end error reporting or reachability testing. So ICMP is the protocol designed for sending error messages and performing connectivity tests like ping.

ICMP handles control messages like error reporting and network diagnostics. Ping uses ICMP Echo Request and Echo Reply to test reachability: you send an Echo Request, and if the destination can be reached, it replies with an Echo Reply. When there are issues, routers can send ICMP error messages such as Time Exceeded (if a packet’s TTL expires) or Destination Unreachable, which helps identify where connectivity breaks down.

UDP and TCP are transport-layer protocols for delivering data—UDP is connectionless and doesn't guarantee delivery, while TCP provides reliable, ordered delivery. ARP maps IP addresses to hardware addresses on a local network and isn’t used for end-to-end error reporting or reachability testing. So ICMP is the protocol designed for sending error messages and performing connectivity tests like ping.