IPv6 basics: what command pings the local host's loopback address (IPv6)?
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Aping 127.0.0.1
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Bping 0.0.0.0
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Cping ::1
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Dtrace 0.0.::1
Answer
Correct Answer: ping ::1
Explanation
Introduction / Context:Loopback addresses provide a way to test the local TCP/IP stack without sending traffic to the network. In IPv6, the loopback address differs from the familiar IPv4 value and is frequently used for troubleshooting and verification.
Given Data / Assumptions:
- Task: Identify the correct syntax to ping the IPv6 loopback.
- We assume a generic operating system CLI where the command is simply ping.
Concept / Approach:IPv4 loopback is 127.0.0.1. By contrast, IPv6 loopback is the single address ::1, which is shorthand for 0:0:0:0:0:0:0:1. It represents the local node only and never appears on the wire.
Step-by-Step Solution:
Recall the IPv6 loopback address: ::1.Construct the ping command using that address: ping ::1.Verify that other listed addresses are IPv4 or invalid syntaxes for this task.Verification / Alternative check:Running ping ::1 should immediately return replies if the IPv6 stack is enabled. Tools may use ping6 on some systems, but the target address remains ::1.
Why Other Options Are Wrong:
- A: 127.0.0.1 is the IPv4 loopback, not IPv6.
- B: 0.0.0.0 is not a host loopback; it represents the default route or an unspecified address in IPv4 contexts.
- D: Not a valid command or address format for loopback testing.
Common Pitfalls:Assuming that IPv4 loopback syntax carries over to IPv6. Always remember that IPv6 uses ::1 for loopback and hexadecimal colon-separated notation.
Final Answer:ping ::1