Preference of Master Name Servers

Matus UHLAR - fantomas uhlar at
Thu Dec 6 14:12:03 UTC 2012

On 05.12.12 17:28, David Hall wrote:
>Question 1:
>In our secondary / slave name servers we specify the master name servers in
>the normal manner:
>zone { type slave; file "m/y/"; masters {
>;;; }; };
>What I have found is that the order of the master name servers does not
>matter and one is used at random. That name server is tried for all AXFR /
>IXFR attempts until it is unreachable.
>Is there a way to set a dedicated preference of which name servers to use

No. all masters are treated equally. Do you know a reason why they should
not? However, if slave received notify from a master, it prefers fetching
from that master, afaik.

>Question 2:
>I am also seeing many entries in our logs that look like:
>Dec 4 10:28:49 mysys named[28103]: zone refresh: retry
>limit for master exceeded (source
>Does this mean that the master name server is unreachable? I have confirmed
>that it is reachable by UDP and TCP.
>Or does it mean that we are hitting one of our limits? Our current values
>serial-query-rate 500;
>transfers-out 300;
>transfers-in 300;
>transfers-per-ns 100;

I would try increasing limits, starting with transfer-in.
you can check in logs or via netstat (or packet dump), how many transfers
were executed in parallel (to know which parameter to increase)

>Question 3:
>We have over 100,000 domains on the name servers. What we see is that once
>we start seeing many of these "exceeded" messages in the logs then our "soa
>queries in progress" will go up significantly and never goes back down.
>We have to shut down the name server and restart it, and then the "soa
>queries in progress" goes down to 0 or 1 and he "exceeded" messages go away.
>Has anyone had a similar problem? If so, how did you resolve this?

with 100k of zones, you must increase limits. Or, use different technique
for distributing changes, e.g. NOTIFY and increase the refresh (and retry)
times to avoid useless timeouts.

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