Is this a valid IPv6 address, 74DC::02BA?

Is 74DC::02BA a valid IPv6开发者_如何学编程 address?

I am trying to break it down, but the various shortcuts are confusing me.

Valid address, yes. See this question. Also, this validator breaks it down nicely.

Correct address, probably not. See RFC 4291, section 2.4, where this address is defined as a Global Unicast address. (the first bits are 0111 0100, which falls under "everything else" in the table) Then see the IPv6 address assignments. You'll notice this address range has not been assigned for use.

Normally you wouldn't see an address written like this, since it contains extra information. (the leading 0 in the second group of digits) So you would probably see it written like 74dc::2ba. (The IETF makes recommendations about how to print IPv6 addresses in RFC 5952.)

If you want to know the rules for IPv6 address shortening, they are specified in RFC 4291, section 2.2.

Here's what I believe to be the best online IPv6 validator (and not just because I wrote it). It will show you the various address forms and show you how the different representations relate to each other (try hovering over each address group).

The "::" means there's all 0s in between the colons. The address expands to 74dc:0000:0000:0000:0000:0000:0000:02ba

IPv6 Address Validator