The IPv4 default route in CIDR notation is translated to



For IPv6 the default route in CIDR is ::/0. How is this transated ? Is it as below ?

IP: ::

mask: ::

  • Don't actually worry about the human-readable IP addresses. The packets and network devices actually use binary numbers for IP addresses, not what you see. For IPv4, it is a 32-bit binary number, and for IPv6, it is a 128-bit binary number. A mask for either is the same length as an address.
    – Ron Maupin
    Jun 27, 2017 at 15:08

1 Answer 1


The default route has a mask length of 0, so it matches anything. The network address with zero length is actually empty, but usually 0 is used.

It's the same with IPv4 and IPv6, just the notation of the latter has changed - :: expands to as many :0000 as are required to get a 128 bit address, so :: by itself expands to 0000:0000:0000:0000:0000:0000:0000:0000.

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