DNS Load Testing Results

Years ago I stopped running BIND as an Authoritative Name Server within my sites - initially this was for security reasons but was quickly eclipsed for maintainability. After running almost every alternate DNS software available we’ve ended up running a mix of PowerDNS and BIND (BIND sneaked back in because of $GENERATE is just to convenient for in-addr.arpa domains). We are running PowerDNS against a Master -> Slave MySQL backend configuration and even though the maintainability is super easy (what could be better than a web interface to a SQL backend) I’ve always been a little paranoid about the potential loss of the DB backend and the loss of our DNS services as a result. I’ve always personally liked the simplicity of Tinydns from DJBDNS but the assumed performance loss on my part has always kept me at bay. Well today I broke down and ran some benchmarks. You could say that the results surprised me a little…

The first test is tinydns-1.05

> ./queryperf -d input_file -s 207.171.12.31

DNS Query Performance Testing Tool
Version: $Id: queryperf.c,v 1.8.192.3 2005/10/29 00:21:12 jinmei Exp $

[Status] Processing input data
[Status] Sending queries (beginning with 207.171.12.31)
[Status] Testing complete

Statistics:

  Parse input file:     once
  Ended due to:         reaching end of file

  Queries sent:         600000 queries
  Queries completed:    600000 queries
  Queries lost:         0 queries
  Queries delayed(?):   0 queries

  RTT max:              0.087436 sec
  RTT min:              0.000055 sec
  RTT average:          0.002845 sec
  RTT std deviation:    0.000680 sec
  RTT out of range:     0 queries

  Percentage completed: 100.00%
  Percentage lost:        0.00%

  Started at:           Tue Nov 20 15:29:18 2007
  Finished at:          Tue Nov 20 15:30:44 2007
  Ran for:              85.816039 seconds

  Queries per second:   6991.700001 qps

Note: Tinydns is running with a 150 MByte data.cdb

The second test is PowerDNS 2.9.21 w/ MySQL:

> ./queryperf -d input_file -s 207.171.11.22

DNS Query Performance Testing Tool
Version: $Id: queryperf.c,v 1.8.192.3 2005/10/29 00:21:12 jinmei Exp $

[Status] Processing input data
[Status] Sending queries (beginning with 207.171.11.22)
[Status] Testing complete

Statistics:

  Parse input file:     once
  Ended due to:         reaching end of file

  Queries sent:         600000 queries
  Queries completed:    600000 queries
  Queries lost:         0 queries
  Queries delayed(?):   0 queries

  RTT max:              0.086546 sec
  RTT min:              0.000401 sec
  RTT average:          0.002508 sec
  RTT std deviation:    0.000601 sec
  RTT out of range:     0 queries

  Percentage completed: 100.00%
  Percentage lost:        0.00%

  Started at:           Tue Nov 20 15:32:11 2007
  Finished at:          Tue Nov 20 15:33:26 2007
  Ran for:              75.741798 seconds

  Queries per second:   7921.649813 qps

The last test is BIND 9.3.3:

> ./queryperf -d input2 -s 207.171.11.32

DNS Query Performance Testing Tool
Version: $Id: queryperf.c,v 1.8.192.3 2005/10/29 00:21:12 jinmei Exp $

[Status] Processing input data
[Status] Sending queries (beginning with 207.171.11.32)
[Timeout] Query timed out: msg id 60619
[Status] Testing complete

Statistics:

  Parse input file:     once
  Ended due to:         reaching end of file

  Queries sent:         600000 queries
  Queries completed:    599999 queries
  Queries lost:         1 queries
  Queries delayed(?):   0 queries

  RTT max:              3.932287 sec
  RTT min:              0.000397 sec
  RTT average:          0.001155 sec
  RTT std deviation:    0.007110 sec
  RTT out of range:     0 queries

  Percentage completed: 100.00%
  Percentage lost:        0.00%

  Started at:           Tue Nov 20 15:36:26 2007
  Finished at:          Tue Nov 20 15:37:02 2007
  Ran for:              35.493465 seconds

  Queries per second:   16904.492137 qps

Needless to say I was impressed (and encouraged) to see that Tinydns wasn’t much slower than PowerDNS in our configuration. However I was blown away that BIND ran twice as fast! I have some serious investigation to do and some further testing. I wonder what tinydns would look like against an SSD or RAMDISK.