The shortest IPv6 addresses
26 points by ache
26 points by ache
I found this was fun! I wonder if there's an equivalent to 4.2.2.1?
I found it fun too!
What is special about 4.2.2.1?
2600:: is from Cogent, so it's a major Internet service provider like Level 3 / Lumen. It's not a DNS, however.
If you ping 0.0.0.0 you typically get the first hop to reply (typically localhost, but your next router if you force an interface). Pinging the 6to4 of 0.0.0.0 (eg 2002::) should probably give you a result from whatever 6to4 gateway you are reaching).
shortest ipv6 is ::, pingable is ::1, 6 symbol 2409:: is shortest public ipv6
Love ::1. It's a bit better than localhost or 127.0.0.1. A bit because using port numbers require writing it as [::1]:8080.
I kind of like how there's more than one local ipv4 address if you want to bind to the same port
I do indeed miss that one. That's why systemd-resolved does not bind a stub resolver to a localhost IPv6 — there isn't an equivalent for binding to 127.0.0.53:53 (which it does to avoid squatting the .1:53).
Perhaps someone knows a trick to get around this?
I'm not sure if you can do something like ::ffff:127.0.0.53 or is that just alternative syntax for an ipv4 address
:: isn't a valid IPv6 address.
Only usable as an invalid address or to mean "any IPv6 address".
::1 isn't usable on the Internet.
I wonder how xTom was able to get those 2a09:: and 2a11:: addresses. Most of the allocations I've seen at the XXXX:: level are large /22 or /32 blocks, but xTom just has /48s.
You need to be careful when querying whois for addresses with many trailing zeroes, because whois servers will typically return just the longest match without mentioning all the shorter allocations. In these cases 2a09:: is a /29 and 2a11:: is a /32, but they have been deaggregated to /48 presumably so that the DNS servers can be anycasted.
The zero-ending addresses feel unnatural to me. I usually started numbering at 1. But maybe that's an IPv4 relic, because I believe the 0 address in a subnet used to be another broadcast address way back? Plus the zero address feels like the subnet identifier, and giving a host that address feels like overloading its meaning.