Hello Michael,
take care to increase the tcpdump buffers. Else it's tcpdump which loose
trafic, not the dns server
Have Fun. Greetings
Martin.Wismer.
tcpdump option -B 131072 helped in my case
PS) this time with my other E-Mail Address
On 10.04.18 02:37, PENG, JUNAN wrote:
Hi, All
I did recursive query capacity test. I used traffic generator to place 15K
QPS traffic to DNS 1 with FQDN1 (Note, FQDN1 can't be resolve by DNS1, it need
to forward it to DNS2 and TTL is set to 0)
But during the test , I found lots of failure , the successful rate is not high
(85%). Then I used TCPdump commands to capture logs in DNS1 , I found the
following things:
Thing 1. DNS query number is larger than response number between traffic
generator and DNS1 . About 15% traffic are dropped by DNS1 .
Thing 2. DNS recursive query number between DNS1 and DNS2 is far less than
query number between traffic generator and DNS1
I want to confirm DNS behavior here:
DNS1 will initiate a recursive query towards DNS2 when first query is coming .
transaction time between DNS1 and DNS2 is about 3 miliseconds. If in these 3
miliseconds, there are other queries with same FQDN are coming, whether all
these queries will be lined up in DNS1 because DNS1 has initiated the same FQDN
resolve request to DNS2 ? if yes, which will explain thing 2 I observed during
the test. After DNS1 gets response from DNS2, then DNS1 will send response
to the all the requests from traffic generator lined up in DNS1 , but
unfortunately , DNS1 seems drop some packets here. There are 15% packet
without response .
Besides, CPU usage is not high in DNS1 , only 30%
Is my understanding correct ? Which parameters in DNS will impact the
performance significantly ? How to do further troubleshooting ?
Thank you very much!!
BR
Michael
_______________________________________________
Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe
from this list
bind-users mailing list
bind-users@lists.isc.org
https://lists.isc.org/mailman/listinfo/bind-users
_______________________________________________
Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe
from this list
bind-users mailing list
bind-users@lists.isc.org
https://lists.isc.org/mailman/listinfo/bind-users
