[AusNOG] Google DNS

Mark ZZZ Smith markzzzsmith at yahoo.com.au
Tue Oct 14 07:39:52 EST 2014


>________________________________
> From: Joshua D'Alton <joshua at railgun.com.au>
>To: Brad Peczka <brad at bradpeczka.com> 
>Cc: "ausnog at ausnog.net" <ausnog at ausnog.net> 
>Sent: Tuesday, 14 October 2014, 1:26
>Subject: Re: [AusNOG] Google DNS
> 
>
>
>I noticed that too. Looks like they are trunking the traffic back to US nodes, Asia nodes probably got out of sync or crashed.
>
>
>OpenDNS appears to be weathering the increased load, people that want local DNS can try switch their 8.8.8.8 to 208.67.222.222  (might be smart long term anyway, to have 2 different upstream DNSs, and with ODNS being on Equinix syd no reason why not).
>

Actually, your ISP's DNS resolvers are better to use, so that e.g., their local Akamai cluster or other local CDN servers are used.

Lower DNS lookup latency can be another reason to use your ISP's resolvers, in particular if you aren't located in Sydney where the ODNS (and Google?) resolvers are and your ISP has resolvers in your state.

These papers (both by people who really know what they're talking about, look them up) suggest a latency target of 100ms to make a system feel like it is responding instantly.

http://www.nngroup.com/articles/response-times-3-important-limits/

http://www.stuartcheshire.org/papers/LatencyQuest.html


I think for a web page, that would mean a maximum of 100ms between when the user pushes the enter key after typing the URL or clicking on it and when the page starts appearing in the browser. So that means there is a 100ms total budget for at least the DNS query and response, the 3 way TCP hand-shake, and then at least one or more TCP segments carrying the first pieces of page data that can be displayed. I don't know what is typical, however I think it is fair to assume that there would be at least 3 TCP segments carrying web page data that need to be received before the browser starts displaying the page (if somebody knows better, I'm interested to know). So that means 8 packets sent and received before the page starts being rendered. 100ms divided by 8 equals 12.6 ms per second maximum trip time for each packet, so the DNS query and response should be complete within 25 ms. Of course, for the whole page to appear 'instant' all of it's content must
 start appearing with 100ms, which might be more of a challenge when it is built using content from many sources e.g., Ad servers, embedded analytics scripts etc.

IIRC, ADSL with interleaving enabled (typical) accounts for around 10ms one way (my ADSL with it disabled is about 3.5ms one way), so of that 12.6 ms per packet maximum budget, there isn't much left after your DNS query reaches your ISP.

If you want to measure your DNS query time, the 'dig' utility prints it at the bottom. 


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>On Mon, Oct 13, 2014 at 10:30 PM, Brad Peczka <brad at bradpeczka.com> wrote:
>
>Up here as well.
>>
>>Though - did anyone else see a bunch of hops just disappear?
>>
>>Regards,
>>-Brad.
>>________________________________________
>>From: AusNOG [ausnog-bounces at lists.ausnog.net] On Behalf Of Rhys Cuff (Latrobe I.T) [rhys at latrobeit.com.au]
>>Sent: Monday, 13 October 2014 7:29 PM
>>To: ausnog at ausnog.net
>>Subject: Re: [AusNOG] Google DNS
>>
>>Back for me...
>>
>>
>>
>>Sent from my iPad
>>
>>On 13 Oct 2014, at 10:26 pm, "Rhys Cuff (Latrobe I.T)" <rhys at latrobeit.com.au<mailto:rhys at latrobeit.com.au>> wrote:
>>
>>I didn't get out the door, both routers were still fanging it so I figured it wasn't that bad,,,
>>Normally my phone would ring before I got anywhere near a terminal too... ;-(
>>
>>
>>
>>Sent from my iPad
>>
>>On 13 Oct 2014, at 10:20 pm, "Tim Raphael" <raphael.timothy at gmail.com<mailto:raphael.timothy at gmail.com>> wrote:
>>
>>I did the same thing - turned right back around having just left home!
>>
>>On Mon, Oct 13, 2014 at 7:18 PM, Rhys Cuff (Latrobe I.T) <rhys at latrobeit.com.au<mailto:rhys at latrobeit.com.au>> wrote:
>>That's something I thought is never see!
>>I ping that every 30 seconds to check for connectivity outside my network.
>>I did the mad dash scramble for nothing this time ;-)
>>
>>
>>
>>Sent from my iPad
>>
>>On 13 Oct 2014, at 10:12 pm, "ANSA SERVERS" <info at ausnetservers.net.au<mailto:info at ausnetservers.net.au>> wrote:
>>
>>Yeah, 8.8.8.8 and 8.8.4.4 is down here in Victoria & Sydney
>>
>>Regards,
>>
>>Matthew Matters  Managing Director / CEO of Aus Net Servers Australia Pty Ltd
>>Management Department  |  Small Business Hosting Sales & Services  |  Aus Net Servers Australia Pty Ltd
>>P  1300 933 038  |  M  0428 028 091  |  E  mmatters at ausnetservers.net.au<mailto:mmatters at ausnetservers.net.au> |  W  www.ausnetservers.net.au<http://www.ausnetservers.net.au/>
>>ABN 25 162 013 194 | ACN 162 013 194 | ARBN B2318 229M | #1 For Dedicated Hosting Solutions For Small Business Since 2007
>>
>>From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Rhys Cuff (Latrobe I.T)
>>Sent: Monday, 13 October 2014 10:12 PM
>>To: ausnog at ausnog.net<mailto:ausnog at ausnog.net>
>>Subject: [AusNOG] Google DNS
>>
>>Hey Guys
>>
>>Has anyone notice Google DNS (8.8.8.8) has stoped working and replying to pings?
>>Seems to be the same with the two providers I use.
>>
>>Thanks
>>
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