Hallo Rico,
die Doku beim ISC sagt:
clients-per-query, max-clients-per-query
These set the initial value (minimum) and maximum number of recursive simultanious clients for any given query (<qname,qtype,qclass>) that the server will accept before dropping additional clients. named will attempt to self tune this value and changes will be logged. The default values are 10 and 100.
This value should reflect how many queries come in for a given name in the time it takes to resolve that name. If the number of queries exceed this value, named will assume that it is dealing with a non-responsive zone and will drop additional queries. If it gets a response after dropping queries, it will raise the estimate. The estimate will then be lowered in 20 minutes if it has remained unchanged.
"time it takes to resolve" könnte man im Sinne von forwarder interpretieren, muss man aber nicht. Interessant ist, dass ich auf 3 NS zugreifen kann, die vergleichbar sind und nur einer hat das "Problem", dieser logt dann auch fleißig sein Autotuning:
14-Mar-2012 07:48:00.911 resolver: notice: clients-per-query increased to 15 14-Mar-2012 08:08:00.911 resolver: notice: clients-per-query decreased to 14 14-Mar-2012 08:13:00.858 resolver: notice: clients-per-query increased to 19 14-Mar-2012 08:33:00.858 resolver: notice: clients-per-query decreased to 18 14-Mar-2012 08:53:00.858 resolver: notice: clients-per-query decreased to 17 14-Mar-2012 09:13:00.858 resolver: notice: clients-per-query decreased to 16 14-Mar-2012 09:23:00.664 resolver: notice: clients-per-query increased to 15 14-Mar-2012 09:38:00.768 resolver: notice: clients-per-query increased to 15 14-Mar-2012 09:58:00.768 resolver: notice: clients-per-query decreased to 14 14-Mar-2012 10:18:00.768 resolver: notice: clients-per-query decreased to 13 14-Mar-2012 11:43:00.745 resolver: notice: clients-per-query increased to 15 14-Mar-2012 11:48:01.788 resolver: notice: clients-per-query increased to 20 14-Mar-2012 12:08:01.788 resolver: notice: clients-per-query decreased to 19 14-Mar-2012 12:28:01.788 resolver: notice: clients-per-query decreased to 18
Da die Doku in den defaults aber von 10 und 100(bei max*) spricht, sind das hier ja noch keine Panikwerte ...
Mit freundlichen Grüßen / Kind regards Ronny Seffner