In computer networking, the utility command ping is used to test connectivity between hosts. Which underlying protocol does ping use to send its echo request and echo reply messages?

Introduction / Context:
The ping command is a widely used troubleshooting tool that helps administrators and users check whether one network host can reach another. When you run ping, it sends small test messages and measures how long it takes to get replies. To understand networking fundamentals, it is important to know which protocol is responsible for those messages. This question asks you to identify the protocol that ping uses under the hood for its echo request and echo reply packets.

Given Data / Assumptions:

• Ping is used to test reachability between IP hosts.
• It sends echo request messages and expects echo replies.
• Options include common Internet protocols such as ICMP, TCP, BootP and ARP.
• We assume basic familiarity with protocol names but not necessarily deep details.

Concept / Approach:
Ping operates using the Internet Control Message Protocol (ICMP). ICMP is part of the IP protocol suite and is used to send control and error messages, including echo request and echo reply. When you ping a host, your machine sends an ICMP echo request to the target, which should respond with an ICMP echo reply if it is reachable and configured to respond. TCP and HTTP are higher level protocols used for reliable data transfer and web communication, not for simple connectivity tests. BootP is used for bootstrapping diskless machines and assigning IP addresses. ARP is used on local networks to map IP addresses to MAC addresses. Therefore, ICMP is the only correct answer for the protocol used by ping.

Step-by-Step Solution:

Verification / Alternative check:
Network analysis tools like Wireshark can capture ping traffic on a network. When you run a capture and then execute ping, you will see ICMP packets with types labelled echo (request) and echo (reply). Technical documentation for ping utilities in Linux, Windows and other systems explicitly mention that ping uses ICMP echo messages. By contrast, traffic for TCP and HTTP appears only when running applications like web browsers or file transfers. ARP packets appear when resolving local IP to MAC mappings, not as part of the ping test itself. This evidence clearly shows that ICMP is the correct protocol associated with ping.

Why Other Options Are Wrong:

• TCP (Transmission Control Protocol): Used for reliable data streams such as web pages and emails; ping does not establish TCP sessions.
• BootP (Bootstrap Protocol): Used to help diskless workstations obtain IP configuration at boot time, not to test connectivity.
• ARP (Address Resolution Protocol): Used to map IP addresses to MAC addresses on a local network; ping relies on ARP indirectly but does not use ARP as its main protocol.
• HTTP (Hypertext Transfer Protocol): Used for web page transfer; completely unrelated to the function of ping.

Common Pitfalls:
Some learners mistakenly select TCP because they associate all Internet communication with TCP/IP and assume ping must use TCP. Others confuse lower level utility protocols like ARP and BootP with the specific signalling used by ping. To avoid these mistakes, remember that ICMP is the special protocol for control and error messages in IP networks, and ping is the classic example of an application that uses ICMP echo request and echo reply messages.

Final Answer:
The ping command uses the ICMP (Internet Control Message Protocol) to send echo request and echo reply messages between hosts.