ipv6 address question

SMR511

Transcender quiz asked me if "::" was a "valid" ipv6 address.

I understand it's the ipv6 unspecified address, and refers to a host in ipv6 stateful configuration.

Just confused by the exact definition of the term "valid" ?

Is there a simple answer here ?

Thanks.

stuh84

Not really a simple answer, but when it means valid, if for example you saw 2001::1111::1/64, this wouldn't be valid, as you can only use the "double colon" trick once per address, otherwise there is no way of knowing which section the 1111 would be.

Another would be doing 20A7::/64, that is a valid prefix, but not a valid address, as there is nothing at the end to signify a host portion in a sense.

It's in a sense like getting something saying would 127.0.0.1, is this a valid host address, which the answer would be not really, as this is the defined loopback address for pretty much every device out there. Same with would 192.168.1.0/24, is this a valid host address, no because its a network address.