Identify the value used when an IPv6 address is not yet known or when a service listens on any local IPv6 address.
Which is the IPv6 unspecified address?
The IPv6 unspecified address is ::/128, with all 128 bits set to zero. It is not a normal assigned destination address.
Detailed explanation
::1Incorrect. ::1 is loopback.
Incorrect. ::1 is loopback.
::Correct. :: is the all-zero unspecified address.
Correct. :: is the all-zero unspecified address.
fe80::Incorrect. fe80:: is in the link-local range.
Incorrect. fe80:: is in the link-local range.
ff00::Incorrect. ff00:: is the start of the multicast range.
Incorrect. ff00:: is the start of the multicast range.
Try it yourself
An example you can run in a temporary verification environment.
python3 -c "import ipaddress; print(ipaddress.ip_address('::').is_unspecified)"Expected result
TrueKey points
- :: means all zero bits
- It represents unspecified
- Distinguish it from ::1
Notes
- Environment: Python 3 ipaddress / 外部通信なし
- Command output formatting can vary slightly by distribution or tool version.
- Run the example in a temporary directory or process when possible.
Foundation review
Read the scope first
Check whether the command acts on the current shell, a new process, an existing process, or a file.
Verify the observable result
Use the supplied command and compare the output with the expected result.