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bbtest shows long DNS runtime, why

list Josh Luthman
Fri, 12 Sep 2008 09:43:36 -0400
Message-Id: <user-c706a10eb1a4@xymon.invalid>

It seems that hobbit resolves all clients via DNS:
  # hostnames resolved  :       40
Why that, I gave all names and it's corresponding IPs at the bb-hosts file?

www.google.com 208.69.36.230 #   <-- this will lookup www.google.com and
ping the IP, if it can't find an A record for it then it will use the IP as
a backup

www.google.com 208.69.36.230 #   testip <--- this will use the hostname for
display purposes, no dns lookup and skip to using the IP for the conn test

I have the same triangular graphs on hotspot networks with multiple APs.
This is normal, as far as I can tell.

Adding 400 hosts and 400 dns queries shouldn't cause too much of a load,
though, if you're worried about the DNS queries taking out the DNS servers
then just tack "testip" to the end of them.  The conn/ping test is awfully
efficient, assuming you're using fping.

Are you using fping or hobbitping?

Josh Luthman
Office: XXX-XXX-XXXX
Direct: XXX-XXX-XXXX
XXXX Wayne St
Suite XXXX
Troy, OH XXXXX

Those who don't understand UNIX are condemned to reinvent it, poorly.
--- Henry Spencer


On Fri, Sep 12, 2008 at 9:38 AM, <user-9219fb9415b1@xymon.invalid> wrote:
Hi

I am running hobbit against 40 clients. Two of these clients are our DNS
servers. Only on these two clients I have enabled the DNS test by adding the
DNS keyword to their bb-hosts line. I wanted to check the function of the
DNS servers

If I look at the statistics of bbtest it looks like this:

Fri Sep 12 15:26:08 2008

bbtest-net version 4.2.0
SSL library : OpenSSL 0.9.7a Feb 19 2003
LDAP library: OpenLDAP 20213

Statistics:
 Hosts total           :       41
 Hosts with no tests   :        1
 Total test count      :       44
 Status messages       :       45
 Alert status msgs     :        0
 Transmissions         :        2

DNS statistics:
 # hostnames resolved  :       40
 # succesful           :       40
 # failed              :        0
 # calls to dnsresolve :       44

TCP test statistics:
 # TCP tests total     :        2
 # HTTP tests          :        1
 # Simple TCP tests    :        1
 # Connection attempts :        2
 # bytes written       :      126
 # bytes read          :      871


TIME SPENT
Event                                            Starttime
 Duration
bbtest-net startup                       1221225968.275331
• Service definitions loaded               1221225968.276931
 0.001600
Tests loaded                             1221225968.281365
 0.004434
DNS lookups completed                    1221225973.283037
 5.001672
Test engine setup completed              1221225973.285332
 0.002295
TCP tests completed                      1221225973.286398
 0.001066
PING test completed (40 hosts)           1221225974.166549
 0.880151
PING test results sent                   1221225974.177932
 0.011383
Test result collection completed         1221225974.177943
 0.000011
LDAP test engine setup completed         1221225974.177944
 0.000001
LDAP tests executed                      1221225974.177945
 0.000001
LDAP tests result collection completed   1221225974.177946
 0.000001
NSLOOKUP tests executed                  1221225974.179452
 0.001506
Test results transmitted                 1221225974.181039
 0.001587
bbtest-net completed                     1221225974.182936
 0.001897
TIME TOTAL
 5.907605


What you see are two mystic things:

It seems that hobbit resolves all clients via DNS:
  # hostnames resolved  :       40
Why that, I gave all names and it's corresponding IPs at the bb-hosts file?

The DNS test runs about 5 seconds for only these 40 clients, maybe that is
because of the first issue:
  DNS lookups completed                    1221225973.283037
 5.001672

If you look at the graph, it gives very scary "triagle curves". I've put a
screenshot here: http://www.trektech.de/test/hobbitgraph.png
The thing seems to have started when I put the DNS keyword to my two DNS
servers. Before it gave a nearly zero line.

I want to add about 400 network switches which should only do a ping test
and I fear that this would extremely increase the runtime of the bbtest.
What can I do to decrease the runtime?

Thorsten Erdmann
ITI/EP68
Mercedes Benz Werk Hamburg
Tel.: +XX-XX-XXXX-XXXX


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