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.

SMR511

Right, yeah I understand zero compression and leading zero compression.

I just mean literally "::"

as in 0000:0000:0000:0000:0000:0000:0000:0000

Is this considered "valid" as an address and if so how ?

amb1s1

SMR511 wrote: »

Right, yeah I understand zero compression and leading zero compression.

I just mean literally "::"

as in 0000:0000:0000:0000:0000:0000:0000:0000

Is this considered "valid" as an address and if so how ?

Is not a valid address because you can't assign that address, for is not valid. It is a valid format, but I think is not a valid address.

mgeorge

::/128 is the same representation of 0.0.0.0 0.0.0.0 in IPv4.

You cannot use this address as a valid host address pe se however it is used to specify an "unspecified" source or destination. For example the default route. Any traffic destined to an unspecified network in the routing table would get routed to the next hop in the route statement.

You should find the following link quite helpful.

Configuring IP Version 6 (IPv6) | Free CCNA Workbook

erfolg255

Yeah I agree in my opinion this is not valid address for ipv6 , it doesn't point any particular network/subnet interface id

Slowhand

You could always poke through the IPv6 Addressing Architecture RFC and see if there's anything in it that sheds some light on the issue.