4 ms·

When a dns request is sent the dns software most of the worlds ISPs uses pulls both the A and the AAAA record, but the AAAA (ipv6) record takes on average 4x lo

When a dns request is sent the dns software most of the worlds ISPs uses pulls both the A and the AAAA record, but the AAAA (ipv6) record takes on average 4x longer than the A record to pull. The dns software short circuits this so what you get back is almost always an ipv4 address. If you're accessing a website, you're almost always going to end up getting its ipv4 address. This is significant, because still the entire internet doesn't support ipv6. (I'm looking at you Sonic.) If website providers can't get a dedicated ipv4 address, they could use some sort of 6to4 like tunnel to support ipv4. But because of the way the current dns software works, by default all of their traffic will run through that ipv4 tunnel. This leaves ipv6 almost exclusively used for p2p or other types of home connections. The future of the internet is shaping up in such a way where websites run over ip4v and end users to have a sort of firewalled ipv4 access, then use ipv6 for everything else. A law that requires ISPs fully support ipv6 may be beneficial.

300bps 7y ago
Is there a reason why certain companies get to retain their originally allocated Class-A netblocks with their 16 million addresses? http://www.aturtschi.com/whois/neta1.html http://www.aturtschi.com/whois/neta1.html Even companies that were given Class-B netblocks with about 65,000 addresses seems a bit wasteful. I remember when I started an ISP in 1996 it was like pulling teeth to get a Class-C with 255 addresses but there Ford sits with 16 million of their own.
- Dagger2 7y ago
  Yes: those netblocks belong to them and you can't take their stuff just because you like the look of it. There aren't enough addresses in v4. Reclaiming one or two /8s here or there won't fix that. Before IANA runout in 2011, we were going through over one /8 per month, and demand has only gone up since then. Those class Bs you're so worried about would last the internet maybe 2 hours each. You can push as many allocations around as you like, but there just plain and simply isn't enough v4.
Dagger2 7y ago
My experience doesn't match that. ISP DNS servers just return the A or AAAA record that they're asked for, and the return time is more or less identical for the two, not 4x longer. All of the client resolvers I've ever used wait for both records to come back, and your DNS resolution returns both sets of addresses. I think OSX does some sort of racing here, but it still gives v6 some amount of head start (~150ms?). Also, Google's published v6 stats say that 29% of their users reach them over v6. That doesn't seem to match with "you're almost always going to end up getting its ipv4 address".
anticensor 7y ago
AAAA record takes 4x as long because v6 addresses are 4x size of v4 addresses.
- Dagger2 7y ago
  I kinda wondered if that was the thought process, but the extra length of the v6 address only adds 12 bytes to the DNS packet. There's still a bunch of other stuff in the packet; dig says the size for my test query goes from 361 bytes to 373 bytes, which is only a 3.3% increase. Even at a rather slow 1 Mbit/s that would only add 100µs to transmit a packet that takes in total ~3ms to transmit. And that 3ms is likely smaller than the latency in the lookup, which is generally going to be the dominating factor.

300bps 7y ago

Is there a reason why certain companies get to retain their originally allocated Class-A netblocks with their 16 million addresses? http://www.aturtschi.com/whois/neta1.html http://www.aturtschi.com/whois/neta1.html Even companies that were given Class-B netblocks with about 65,000 addresses seems a bit wasteful. I remember when I started an ISP in 1996 it was like pulling teeth to get a Class-C with 255 addresses but there Ford sits with 16 million of their own.

Dagger2 7y ago
Yes: those netblocks belong to them and you can't take their stuff just because you like the look of it. There aren't enough addresses in v4. Reclaiming one or two /8s here or there won't fix that. Before IANA runout in 2011, we were going through over one /8 per month, and demand has only gone up since then. Those class Bs you're so worried about would last the internet maybe 2 hours each. You can push as many allocations around as you like, but there just plain and simply isn't enough v4.

Dagger2 7y ago

My experience doesn't match that. ISP DNS servers just return the A or AAAA record that they're asked for, and the return time is more or less identical for the two, not 4x longer. All of the client resolvers I've ever used wait for both records to come back, and your DNS resolution returns both sets of addresses. I think OSX does some sort of racing here, but it still gives v6 some amount of head start (~150ms?). Also, Google's published v6 stats say that 29% of their users reach them over v6. That doesn't seem to match with "you're almost always going to end up getting its ipv4 address".

anticensor 7y ago

AAAA record takes 4x as long because v6 addresses are 4x size of v4 addresses.

Dagger2 7y ago
I kinda wondered if that was the thought process, but the extra length of the v6 address only adds 12 bytes to the DNS packet. There's still a bunch of other stuff in the packet; dig says the size for my test query goes from 361 bytes to 373 bytes, which is only a 3.3% increase. Even at a rather slow 1 Mbit/s that would only add 100µs to transmit a packet that takes in total ~3ms to transmit. And that 3ms is likely smaller than the latency in the lookup, which is generally going to be the dominating factor.