lost DNS queries

[Frank Altpeter]

Hi list,

I'm trying to resolve a strange problem on my DNS resolver system for some
time now, and still have no clue where to catch the reason. Perhaps
someone here has some hints for me...

The prerequisites:

DNS Server with FreeBSD 6.2-RELEASE-p4 running bind as resolver (hardware
sufficient, e.g. dual Xeon 3.0 GHz with 2GB RAM, OS on SCSI RAID1).

DNS client machine connected via HP ProCurve switch and in the same VLAN
as the DNS server machine.

Test software: dnsperf


Command executed: dnsperf -d /tmp/input-10000.txt -s ${DNSSERVER} -c -A



Result output of the command:
----------------------------------------------------------------------------
  Parse input file:     once
  Ended due to:         reaching end of file

  Queries sent:         10000 queries
  Queries completed:    9770 queries
  Queries lost:         230 queries

  Returned  NOERROR:    7235 queries
  Returned SERVFAIL:    107 queries
  Returned NXDOMAIN:    2428 queries

  Avg request size:     41 bytes
  Avg response size:    184 bytes

  Percentage completed:  97.70%
  Percentage lost:        2.30%

  Started at:           Tue Aug 28 12:22:51 2007
  Finished at:          Tue Aug 28 12:25:30 2007
  Ran for:              159.355209 seconds

  Queries per second:   61.309574 qps
----------------------------------------------------------------------------

I tweaked several settings on the dns server to reduce the percentage
lost:

sysctl net.inet.icmp.icmplim=1024
sysctl net.inet.raw.recvspace=65536
sysctl net.inet.udp.recvspace=256000
sysctl net.inet.tcp.sendspace=65536
sysctl net.inet.tcp.recvspace=65536
sysctl kern.ipc.somaxconn=512
sysctl kern.ipc.maxsockbuf=8388608


but still i'm not able to find a reason why so much queries are lost and i
don't see any reason for this. It even happens when dnsperf is started
directly on the dns server.


Does anyone has an idea where to search for this problem?


Le deagh dhùraghd,

	Frank Altpeter

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