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Subject: Parent DNS irresponsivity

19/01/2009 23:39 AnrDaemon:
I have a LAN that connected to the 2 providers, and I set up SmallSrv to obtain DNS records from both routers.

. IN NS ns1.darkdragon
ns1.darkdragon IN A 192.168.1.1

. IN NS ns2.darkdragon
ns2.darkdragon IN A 192.168.1.2

Idea was that if one connection fails, another will server as backup.
But SmallSrv continue to abuse first DNS server in all cases, even if common recommendation is to randomly select one of the listed server to reduce load.

What I want to know, if it is at all possible to make this scheme work? I've tried to setup real name servers instead of routers, but it turns in the same problem if not worse.

And what happened to the russian forum, by the way?
20/01/2009 20:20 Max:
What scheme do you mean? May be, in common recommendation you can find something about using provider's DNS servers instead real root server?

If you use root server as real root server (the option "Recursion calls begin from defined servers" is not selected) the sequence is not matter because the program will ask them only once per 2-3 days to get NS servers of primary zones like .com ,.org , .net, etc. Next request will be to the NS servers of zones, that will be cashed.

If you would like to use provider's DNS then preferred servers must be directed first. If provider's servers don't reply the program will ask root server, it take more time but probably worked... If the program will be randomly select one of the listed root server each time, it will be slowly.

You may direct little value for timeout in option: "Timeout, before re-send request again." for case when one of your provider down.


Russian forum still working alike this English forum.

16/02/2009 00:33 AnrDaemon:
If primary DNS fails, root servers will fail too.
So, what the purpose to list more than one DNS server in SmallSrv config?
16/02/2009 12:08 Max:
Why? One DNS may down, but another, it is independent servers -- will work.


17/02/2009 22:02 AnrDaemon:
Well, I see some misunderstanding... let me explain it in clear.

My local network connected to two routers.
Router A connected to internet directly.
Router B connected to other (regional) LAN, which also connected to internet.
On my DNS server (which is smallsrv), I have B as default gw and primary DNS server, because I need DNS resolution for regional LAN.
Router A listed as second DNS server.

If router B failing to resolve name, you said, it's going to root servers... through default GW... which is B again...

My question is... at which point it will as secondary DNS server then?

# DNS settings
hosts="C:\etc\hosts"
dnscache=2
dnstimeout=200
dnsupl
dnscachefile="nul"
dns_range="192.168.1.1-192.168.1.14,127.0.0.1"
dns_deny=""
dns6_range="::1-FFFF:FFFF:FFFF:FFFF::"
dns6_deny=""

hosts:
. IN NS ns1.darkdragon
ns1.darkdragon IN A 192.168.1.1

. IN NS ns2.darkdragon
ns2.darkdragon IN A 192.168.1.2

# local domain definition.
...
17/02/2009 22:03 AnrDaemon:
**it will ask

sorry for spelling.
17/02/2009 23:40 Max:
In your host file defined two NS servers only. Both in LAN B -- this mean, If router B down, then DNS will not work.
If you direct real root server after NS servers from LAN B, then when router B will down, the server will resolve names begin from root servers. It will slowly but it will work.

For your purpose you may use $IF_DOWN directive to change IP of root server:
$IF_DOWN 192.168.1.1:53 60 192.168.1.1=10.1.0.2

21/02/2009 01:46 AnrDaemon:
There's no such thing like "LAN B". I have one home LAN with two router. As you see from hosts definition, both NS in the same network.

My question remains unanswered - at which point smallsrv will ask second nameserver listed in hosts?
To now, from logs, I only see it directing all requests to 192.168.1.1, even if it permanently returning "host not found" or plainly failing to respond in time.
21/02/2009 12:23 Max:
Next request (to next server in list) will send when no reply for timeout.
25/02/2009 16:34 AnrDaemon:
Amhm... well.
That means, it will never ask second server. :(

smallsrv timeout at least the same 2 sec as system name resolution timeout. Is there any way to reduce it? Half a second would be great.
26/02/2009 02:09 Max:
You may direct timeout in DNS server's options:
"Timeout, before resend request again. In milliseconds"


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