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Will Vista Overload the DNS?
Jamie Northern writes, "Thanks to new directory software, Windows Vista could put a greater load on Internet DNS servers. But experts disagree over whether we're headed for a prime-time traffic jam or an insignificant slowdown. Paul Mockapetris,inventor of DNS, believes Vista's introduction will cause a surge in DNS traffic because the operating system supports two versions of the Internet Protocol (IPv4 and IPv6). David Ulevitch, chief executive at OpenDNS, a provider of free DNS services, said Vista's use of IPv6 will not disrupt the Internet at large. 'DNS can be improved, but predicting its collapse is just spreading FUD.'"
Linux and MacOS X are both capable of having both IPv6 and IPv4 stacks, and in many cases this is active by default. Why would Vista cause any more problems?
If you have a good setup then you will have a lookup cache on your local machine storing both IPv6 and IPv4 addresses for each site. Therefore only one lookup should need to be done.
Jumpstart the tartan drive.
For a guy who "invented DNS," he sure doesn't seem to have much of a grasp of how the current DNS infrastructure works.
First off, most DNS servers are very lightly loaded. DNS in general doesn't take a whole lot of traffic (relative to other protocols), and most DNS servers are way overpowered for what they need to do.
Secondly, as the article states, Vista is not going to just blindly do two queries, one IPv4 and the other IPv6, for every request. It is a little more intelligent than that (shocking, I know). For systems that don't have an IPv6 address (which will be virtually all of them given the current adoption rate of IPv6), no IPv6 DNS queries will be done at all.
Linux and other Unix-like OSes have supported IPv6 for years, and they haven't managed to kill DNS yet. Most Vista installations, like most Linux installations these days, are going to have IPv6 disabled anyway, so this is not going to have any real impact at all.
That's just a bunch of meaningless technical jargain. They seem to forget that DNS overhead was down by 34% since last year and it's projected to drop by another 20% midway through 2007. So any 'slow downs' as they call them would be soaked up by the rent left from the overhead surplus. yingers
When working with response time instead of %CPU, the curve is quite different from what one normally sees.
It starts off level, at some number of milliseconds (mostly the round-trip time) and stays that way until the load hits 100%, then increases rapidly and without bound.
For example, if a lookup takes 1/10 second, it will continue to take 1/10 second until there are 10 requests per cpu per second.
After that a queue builds up, and the requests are delayed. Brutally. At a mere 100 requests/second, the delay is 10 seconds, instead of one tenth.
Now imagine that at the huge loads the DNS servers typically handle.
When someone says "they've hit the knee of the curve", he really means "they're about to fall in the toilet" (;-))
--dave
davecb@spamcop.net
It probes for ipv6 first, then falls back to ipv4. This is the default setting for many unix systems as well. You usually find your system running slowly, then find a setting for this and turn it off to eliminate the timeout delay.
As for how big a spike it can cause, see this for the effect of Windows' active directory update scheme on the root servers.
Intron: the portion of DNA which expresses nothing useful.
When I say NAT, I don't mean firewall, I mean Network Address Translation. True, its function is usually performed by a firewall or gateway, but I'm not talking about stateful inspection or anything like that. NAT simply replaces the source and destination addresses in IP packet headers to allow multiple private IPs to use a single public IP (keeping track of conversations and such). More importantly for security, however, NAT prevents uninitiated outside connections from reaching devices inside the private network unless specifically configured as a server. What this means is that even without a firewall, a worm exploiting some neat new Vista "feature" will not be able to penetrate NAT to access ports on the not-yet-patched computers inside.
Yes, you can install IPv6 stack for WinXP with a single command. However, the stack does not support DNS query in IPv6 (not AAAA query via IPv4), which kind of destroy the hope of deploying pure IPv6 network.
Nobody seems to understand how IPv6 DNS works.
First off, when your box asks for any address from your dns server, the dns server hits the public internet root name servers and gets the Start of Authority (SOA). This tells your dns server (or you if you wanna set up one locally) where to get DNS information for that domain. None of that changes with IPv6.... NOTHING. It can still make all of those requests over IPv4 and it doesnt' matter and it will never duplicate the requests.
Now that your dns server knows where to get the zone file for that address it goes and gets it from the SOA. If both IPv6 and IPv4 are supported then you'll have a main A record and main AAAA record (quad A) in that zone. Which ever one comes first should be the one that is honored, this is so that the people who own the domain can specify if they prefer you to use IPv6 or IPv4 (Note: WindowsXP has a bug in which it ALWAYS uses the IPv4 address if one exists).
So the increase in traffic is only between you and your dns server if the dns server is configured to get the entire zone file and not just query for a single entry (this is the proper way to configure a dns server that intends on supporting IPv6 because if you don't get the entire zone file then you don't know which protocol to prefer, it's also just a good idea and you should be getting the zone's TTL and honoring at well -- I'm anal about this by the way). If your dns server is configured to query for each entry then the traffic is only between that dns server and the start of authority. So this will not increase the load on the world wide traffic to root name server AT ALL.
Of course it runs NetBSD. BTC: 1NT7QvbetmANwaMzhpVL6
However, the stack does not support DNS query in IPv6 (not AAAA query via IPv4), which kind of destroy the hope of deploying pure IPv6 network.
:)
You don't need a "pure IPv6 network".
You can give private IP addresses (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) to users' computers for talking with your recursive DNS servers.
They can use IPv4 to talk to your DNS server, and IPv6 to talk to the Internet (or anyplace else they need a globally unique IP address).
Of course, you'd need to use non-Microsoft software on your recursive DNS servers. But BIND runs on Windows, so it's not a huge problem.
Guess you didn't get it .
Microsoft disabled raw socket support in XP SP2 to prevent exactly those types of attacks as outlined by the grc site.
p pro/maintain/sp2netwk.mspx
http://www.microsoft.com/technet/prodtechnol/winx
"This change limits the ability of malicious code to create distributed denial-of-service attacks and limits the ability to send spoofed packets, which are TCP/IP packets with a forged source IP address."
Not so FUD after all.
This is Dan Kaminsky, from the article.
:) Paul knows DNS. It's his creation. But you'll note in this story that Joris Evers can't actually find anyone who agrees with Paul.
Here's what I threw on my blog on this matter. Note, the fact that this got presented as even a debate annoyed me enough to start posting on my site again.
--
Paul Mockapetris says Vista is going to take down the Internet's DNS infrastructure. Paul is the inventor of DNS; I met him at Black Hat last year and was half starstruck, half relieved he didn't hate me for the things I'd done to his creation
There's a reason.
First, while there are indeed a couple underprovisioned name servers, there's far more that have lots and lots of slack capacity. You need slack capacity to deal with shock load. The networks that would fail because of Vista's release, would fail because of a three day weekend.
Second, Vista's not getting deployed all at once. This is no service pack that's deployed to a hundred million desktops via Windows Update! Mockapetris is correct in that there will be a noticable increase in DNS traffic, but that increase will be spread out over the course of a couple years. Slow increases like this tend not to cause the sort of catastrophic failure that Mockapetris refers to.
Finally, and most importantly (in the sense that Mockapetris should know better): Most of the work done to service the IPv6 request, is cached and available to service the IPv4. To complete a DNS lookup, you have to locate a particular server, known as the authoritative server for a domain. The same authoritative server that hosts the IPv6 (AAAA) record also hosts the IPv4 (A) record. So even if Vista sends twice the traffic, the upstream nameserver is certainly not experiencing twice the load.
Full disclosure: Microsoft has had me looking at Vista for much of this year, as part of their "Blue Hat Hacker" external pen-testing squad. But then, Mockapetris has written a really impressive name server for his company, Nominum, that can handle about 4x the load of BIND. But this isn't about who we are; it's about what is or isn't going to collapse. There are things to worry about. This isn't one of them.
Why yes, Geoff Huston has analyzed the problem pretty thoroughly:
http://www.potaroo.net/tools/ipv4/
So, we're looking at just under 6 years.
BTW, Geoff Huston is a guru.
A friend of mine sent this to me this morning when we were discussing this:
.LOCAL TLD. The last time I looked, about 40% of the traffic to global name servers was this bogus windows shit. If Vista fixes that, then its release will be a net positive.
"I manage the operation of about 70% of the world's root DNS servers, and run authoritative TLD servers (mostly secondaries) for about 30% of the world's TLDs (mostly CCtlds). We measure carefully.
IPv6 isn't even 0.01% of the total, and doesn't matter.
The real load on name servers comes not from IPv6 but from Windows machines flooding the world with RFC1918 in-addr requests and with lookup requests in the
We started and sponsor the AS112 Project ( http://public.as112.net/ ) to try to mop up some of the Windows mess. No one believes that we'll need to extend it to IPv6, but we're paying attention."
He is of course right, the nonsense windows does has been a problem for years.
Need Mercedes parts ?