recursive queries fail with high load?

Dmitry Rybin kirgudu at corbina.net
Mon Feb 26 15:12:09 UTC 2007


Compile named without threads and whith -DISC_MEM_USE_INTERNAL_MALLOC.
Whith BIND 9.4.0 - I have much smaller load on my server.

Chris Michels wrote:
>  
> I have 3 DNS servers running bind 9.3.2.  Two of them are failing to resolve
> recursive queries.   Both of these servers have a higher load because they
> are used by our spam filtering software.  I have increased the
> recursive-clients option on both servers.  It seems like recursive queries
> are just taking a long time and timing out.   What is going on here or where
> should I be looking for what is wrong?
> 
> A dig of a random name returns:
> 
> [root at ruby named]# dig www.websudoku.com[1] @ns2.nau.edu
> 
> ; <<>>DiG 9.2.4 <<>>www.websudoku.com[2] @ns2.nau.edu
> ; (1 server found)
> ;; global options:  printcmd
> ;; connection timed out; no servers could be reached
> 
> But if I set the timeout high it returns:
> 
> [root at ruby named]# dig +time=240 www.websudoku.com[3] @ns2.nau.edu 
> 
> ; <<>>DiG 9.2.4 <<>>+time=240 www.websudoku.com[4] @ns2.nau.edu
> ; (1 server found)
> ;; global options:  printcmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 50071
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 0
> 
> ;; QUESTION SECTION:
> ;www.websudoku.com.             IN      A
> 
> ;; ANSWER SECTION:
> www.websudoku.com[5].      3600    IN      CNAME   websudoku.com.
> websudoku.com.          3600    IN      A       66.39.22.227
> 
> ;; AUTHORITY SECTION:
> websudoku.com.          3600    IN      NS      ns00.ns0.com.
> websudoku.com.          3600    IN      NS      ns97.pair.com.
> 
> ;; Query time: 20270 msec
> ;; SERVER: 134.114.138.3#53(134.114.138.3)
> ;; WHEN: Sun Feb 25 22:27:40 2007
> ;; MSG SIZE  rcvd: 112
> rndc status shows:
> 
> number of zones: 746
> debug level: 0
> xfers running: 0
> xfers deferred: 0
> soa queries in progress: 0
> query logging is OFF
> recursive clients: 1441/5000
> tcp clients: 0/1000
> server is up and running
> 
> stats show a high percentage of failures
> 
> +++ Statistics Dump +++ (1172467505)
> success 305925
> referral 114
> nxrrset 15781
> nxdomain 335350
> recursion 529820
> failure 303309
> --- Statistics Dump --- (1172467505)
> 
> 
> 



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