IPAddress::IPv6::Unspecified

The address with all zero bits is called the unspecified address (corresponding to 0.0.0.0 in IPv4). It should be something like this:

0000:0000:0000:0000:0000:0000:0000:0000

but, with the use of compression, it is usually written as just two colons:

::

or, specifying the netmask:

::/128

With IPAddress, create a new unspecified IPv6 address using its own subclass:

ip6 = IPAddress::IPv6::Unspecified.new
ip6.to_s # => => "::/128"

You can easily check if an IPv6 object is an unspecified address by using the IPv6#unspecified? method

ip6.unspecified? # => true

An unspecified IPv6 address can also be created with the wrapper method, like we've seen before

ip6 = IPAddress.new "::"
ip6.unspecified? # => true

This address must never be assigned to an interface and is to be used only in software before the application has learned its host's source address appropriate for a pending connection. Routers must not forward packets with the unspecified address.

ip6 = IPAddress::IPv6::Unspecified.new
ip6.to_string # => "::/128"