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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 9:31:38
Message-ID: 53BFAEFA.7050808 () telefonica ! net
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On 2014-07-11 07:56, Linda Walsh wrote:
> Carlos E. R. wrote:

> Your router for DNS?   How odd.  I've never heard of having a linux box,
> then using a small underpowered microprocessor to do DNS....

Home routers are typically running Linux or a variant, and all the home
routers I tried have what /they/ /call/ a dns service, which can be just
a re-sender to the DNS addresses negotiated with the ISP.

It makes things easy, while using dhcp for some devices, to get a DNS
server for the entire home network, guaranteed to be alive. Not all my
home devices can configure a DNS service at all, in their local network
configuration. For instance, on my ebook I can't, so the mandatory DHCP
service has to supply one.

And on those machines, like computers, where you really can configure
the network, it is easier to tell them to ask the router address for DNS
queries, which typically works with my laptop even when moving from
place to place.

The alternative is to configure them with the DNS address of my provider
(I prefer not to use google's if I can avoid it). But my provider do not
publish them, and they can change. And my laptop can be connected to
different providers.


So telling all those machines to use the local router for that service
is simply one complication less to think about.


> Um... why are you using a router?   My linux box does my routing and DNS
> (and a score or
> two of other things).  I.e. your linux box has to do queries to resolve
> DNS.

Because it is there, full time.

I need "something" to connect to my ISP ADSL, however you call that box,
and an ADSL router does just that out of the box.

So I have a small box, that connects to the phone line, that has wifi,
does dhcp, does dns (but faulty in this particular model), does a few
other things, and uses very little electricity, which is important for me.

Yes, I know that a small computer can do way more. But, I would need
"something" to connect to the ADSL, then a linux box with two eth ports,
and a wifi access point, then a switch. That's a total of three boxes
minimum, all draining power and using space, and possibly administration
time.

I don't have a suitable machine for that task, besides the existing
router. So I don't see a justification for the hassle. If I were setting
up a larger local network, then certainly I would. And more things, like
proxy, firewall, etc.


> If it does so from the root, then it has to send out ...  1 request to a
> root server to see
> who owns the TLC, then to the TLC to see who owns the domain... then to
> the domain to see
> what the ip of it's servers is...

I consider asking the root servers myself "not polite".


> That's about 3 requests minimum (assuming a cold cache)...
> 
> The thing is, a small solid-state router won't have alot of cache memory to
> hold many entries.  You are talking to a server that likely only has to

For that reason I run bind cache on my computer ;-)
I have done that since about 1999.


> So color me unconvinced.. but having your lower powered router look up
> a DNS addr, is alot more likely to run into traffic contention problems
> given the round trips to all the authoritative servers for each level.  

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.

-- 
Cheers / Saludos,

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


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