[prev in list] [next in list] [prev in thread] [next in thread] 

List:       opensuse
Subject:    Re: [opensuse] Re: When I have downloads running, DNS fails.
From:       "Carlos E. R." <robin.listas () telefonica ! net>
Date:       2014-07-11 14:42:37
Message-ID: 53BFF7DD.90705 () telefonica ! net
[Download RAW message or body]

On 2014-07-11 16:09, Linda Walsh wrote:
> Carlos E. R. wrote:
>>
>> I consider asking the root servers myself "not polite".
>>   
> Well unless you speak named protocol, you'd be wasting their time.
> I usually let named talk to them directly.

I don't.

> How else do you do a domain lookup?

By asking the DNS server of my ISP, which will respond directly if it
has the answer, or query the root servers for me. This diminishes the
load on the root servers, and is considered the polite behaviour.
Everybody on a particular ISP asks that DNS server, concentrating the
load on it, not on the root servers.

A domain, in this context, is opensuse.org, or google.com.


> You indicated some concern over having all your DNS
> entries forwarded to someone else for resolution, but if you
> rely on someone else looking up things for you, that's
> exactly what you are doing -- forwarding all your DNS entries
> to someone else to resolve for you...

No.

I expressed concern on handling my queries to google, specifically,
because it does data mining on them. My ISP, as far as I know, does not.

>> For that reason I run bind cache on my computer ;-)
>> I have done that since about 1999.
>>   
> ----
>    Ahh.. but we are discussing the case where the DNS lookups
> are not in an intermediate cache... ;-)

All my queries are cached by bind or dnsmasq on their respective
computer. But those entries time out eventually and they are deleted, so
that when needed again the local cache dns server has to ask outside, again.

They are, and they were. For many years.



>> My previous router, which was a cheap model supplied by the ISP, did
>> this DNS service just fine. It was not a problem. Other routers I have
>> used do it fine. It is just this particular brand and model which fails.
>> In fact, it is the first time I see this particular issue.
>>   
> ----
> Are you comparing apples w/apples?
> 
> I.e are your different lines the same speed and capacity??
> 
> Are your computers the same now as then?  Or would they be able to
> ask for traffic more quickly and possibly saturate your local line to
> the exclusion of other traffic (like DNS)?

The paragraph above refers mainly to the same ADSL pipe, and the same
computers, with the same software. Only the router changed, about a year
ago, and then my DNS problems started.

The laptops have met other places with different routers.

And I have been on other places, with different computers, all
configured to use their local router as DNS server.


> As someone else mentioned, your newer model router might have bigger
> io-buffers, and might give better download performance, but worse
> interactive
> performance during a download.

It is a better and newer router, more capable, connected on the same old
1 mbit/s pipe.

So no, I can not accept that it performs worse, and just on a single
service.



> Until your DNS traffic is prioritized above the "ACK"s on download streams,
> which many home routers have implemented  to improve throughput,
> high download saturation may slow down DNS communication -- especially
> where the
> resolution is done on your end (vs. always using someone else's DNS server,
> maybe your ISP's or google's).
> 
> The ACKS from the DNS traffic have to compete with your download traffic,
> and unless you use ingress filtering, DNS could become unresponsive due
> to the download.
> 
> This effect can be worsened by DNS's defaulting to UDP as it doesn't have
> tcp's auto-correction mechanisms.
> 
> also, on QOS, everything else doesn't need to set QOS.
> 
> Only the traffic you want to prioritize.
> Traffic w/o the QOS settings is placed in "the bulk" is given "normal"
> "best-effort" -- so it can speed up some traffic by prioritizing some
> traffic over 'bulk' (unrated).


All that applies as well to my DNS cache server on my computer, which
traversing the same "saturated" router, manages to do DNS queries just
fine, with a saturated internet pipe.


-- 
Cheers / Saludos,

		Carlos E. R.
		(from 13.1 x86_64 "Bottle" at Telcontar)


["signature.asc" (application/pgp-signature)]
-- 
To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org
To contact the owner, e-mail: opensuse+owner@opensuse.org


[prev in list] [next in list] [prev in thread] [next in thread]