In IPv6, which address is the loopback address, equivalent in role to 127.0.0.1 in IPv4?
LPIC-1 Exam 102-500, objective 109. Networking fundamentals easy
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The options
Not correct ::
Wrong. :: is the all-zeros unspecified address. A socket bound to :: listens on all IPv6 addresses; it is not the loopback destination.
Not correct fe80::1
Wrong. fe80::/10 is the link-local range. Every IPv6 interface gets a link-local address, but it is scoped to a single link and is not the loopback.
Correct ::1
Correct. ::1 is 127 zero bits followed by a one, the IPv6 loopback address assigned to the lo interface as ::1/128.
Not correct ff02::1
Wrong. ff00::/8 is the multicast range; ff02::1 is the all-nodes link-local multicast group, roughly the IPv6 stand-in for a broadcast to every host on the link.
Why
IPv6 loopback is ::1/128, a single address rather than IPv4's whole 127.0.0.0/8 network. Other ranges worth recognising: :: (unspecified), fe80::/10 (link-local), fc00::/7 (unique local, the rough analogue of RFC 1918 private space), and ff00::/8 (multicast). IPv6 has no broadcast address at all; multicast replaces it.
Where this comes from
- Cited
- LPI exam objective 109.1
- What it says
- Recognise the common IPv6 address types and notation.
Practise this
Reading one question is not practice. The trainer will draw a set from objective 109 and space the ones you get wrong.