200-901 Question 174
Single answerA network engineer is troubleshooting connectivity issues between a client and a web server. The engineer decides to use the ping command to test connectivity. Which protocol and layer of the OSI model does the ping command primarily operate at?
- A
TCP at the Transport layer
- B
ICMP at the Network layer
- C
UDP at the Transport layer
- D
DNS at the Application layer
Show answer and explanation
Correct answer: B
Explanation
The ping command is a diagnostic tool used to test network connectivity between devices. It uses ICMP (Internet Control Message Protocol), which is part of the Network layer in the OSI model. ICMP sends echo request and echo reply messages to determine if a device is reachable and measure round-trip time.
- A. Incorrect.
Incorrect: The
pingcommand does not use TCP, as it is designed for connectivity testing and does not establish a connection-oriented session. - B. Correct.
Correct: The
pingcommand uses ICMP (Internet Control Message Protocol), which operates at the Network layer of the OSI model, to send echo request and receive echo reply messages. - C. Incorrect.
Incorrect: The
pingcommand does not use UDP, as it is not a connectionless transport-layer protocol for testing connectivity. - D. Incorrect.
Incorrect: The
pingcommand does not rely on DNS, which operates at the Application layer, as it directly uses IP addresses or resolves hostnames before initiating the ICMP tests.