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Lollo
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Strange DNS behaviour, randomly fails resolving

Sat Sep 01, 2007 7:08 pm

Hi there,

I just started noticing a strange DNS behaviour on my RouterOS box. Let's say that's my network:

PC -> RouterOS 5Ghz CPE ---> Ap --> Bridge ---> PPPoE Server

My PC DNS points to my first hop (RouterOS CPE). RouterOS CPE's DNS points DNS to PPPoE Server Address. PPPoE Server has DNS addresses provided by my ISP.

When I try to resolve certain domain names, it fails and marks them in IP->DNS->Cache with a "N"

If i try to resolve the name directly by using OpenDNS or my ISP DNS, it just works flawlessly. If I just put my ISP DNS in my CPE DNS, it works.

Could it be a bug or something?
 
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Equis
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Re: Strange DNS behaviour, randomly fails resolving

Sun Sep 02, 2007 11:50 am

YES, I can say I have the same bug

DNS works for a few days under high load then stops resolving untill next reboot.

I wonder if it is alot of work to out service watchdog in RouterOS?
 
Lollo
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Re: Strange DNS behaviour, randomly fails resolving

Sun Sep 02, 2007 12:10 pm

Well, at least I know I'm not the only one experiencing that weird behaviour :(

Should we file a bug?
 
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Equis
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Re: Strange DNS behaviour, randomly fails resolving

Sun Sep 02, 2007 12:13 pm

I have spoken to MT about it but they could not replecate the problem.

Perhaps if you did a supout and mention that you have spoken to another pwerson with this problem.

I ended up just installing a Bind DNS but would love to just use MT

:-)
 
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Equis
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Re: Strange DNS behaviour, randomly fails resolving

Sun Sep 02, 2007 12:19 pm

One Day I'll get around to testing this with V3, hopefully it may be already fixed :-)
 
Lollo
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Re: Strange DNS behaviour, randomly fails resolving

Sun Sep 02, 2007 12:31 pm

Eheheh :) Ok, I'll make a support request :)

So you solved by using a separate DNS server (bind)? I think I have to follow your steps too, but that's a real pity, I really would like to see things work just with MT :)
 
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Equis
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Re: Strange DNS behaviour, randomly fails resolving

Sun Sep 02, 2007 12:42 pm

Yes

I have always had my own Bind dns server but liked having it on the core router.

It mean if power was off for a long time and ups went flat I could run router & radios off 12 volt car Battery and system would still run :-)
 
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omega-00
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Re: Strange DNS behaviour, randomly fails resolving

Mon Sep 03, 2007 5:06 am

Why not just set the clients to use openDNS directly?

Pretty much guaranteed better uptime anyway :-)
 
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Equis
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Re: Strange DNS behaviour, randomly fails resolving

Mon Sep 03, 2007 5:10 am

For me I like to Cache DNS

But that would be a good option for a secondary.
 
Lollo
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Re: Strange DNS behaviour, randomly fails resolving

Mon Sep 03, 2007 9:56 am

Why not just set the clients to use openDNS directly?

Pretty much guaranteed better uptime anyway :-)
Well, they're way too slow (200 to 300ms latency) from here :|

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