[hobbit] bbtest shows long DNS runtime, why

Hubbard, Greg L greg.hubbard at eds.com
Fri Sep 12 15:54:17 CEST 2008

Add the "testip" flag to each host and Hobbit will not try to resolve
the name.
When you add the "dns" flag, Hobbit will test the DNS server on that
You might also keep in mind that DNS results are usually cached by the
resolver on each machine until they expire, and this happens at an
operating system level.  However, Hobbit uses a specific DNS support
package (perhaps to make the code more portable) -- I have seen it hang
when the DNS servers are not exactly correct, so using "testip" is a
good defence mechanism.

From: thorsten.erdmann at daimler.com [mailto:thorsten.erdmann at daimler.com]

Sent: Friday, September 12, 2008 8:38 AM
To: hobbit at hswn.dk
Subject: [hobbit] bbtest shows long DNS runtime, why

	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
	 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
	Event                                            Starttime
	bbtest-net startup                       1221225968.275331
	Service definitions loaded               1221225968.276931
	Tests loaded                             1221225968.281365
	DNS lookups completed                    1221225973.283037
	Test engine setup completed              1221225973.285332
	TCP tests completed                      1221225973.286398
	PING test completed (40 hosts)           1221225974.166549
	PING test results sent                   1221225974.177932
	Test result collection completed         1221225974.177943
	LDAP test engine setup completed         1221225974.177944
	LDAP tests executed                      1221225974.177945
	LDAP tests result collection completed   1221225974.177946
	NSLOOKUP tests executed                  1221225974.179452
	Test results transmitted                 1221225974.181039
	bbtest-net completed                     1221225974.182936
	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
	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
	Mercedes Benz Werk Hamburg
	Tel.: +49-40-7920-2593
	If you are not the intended addressee, please inform us
immediately that you have received this e-mail in error, and delete it.
We thank you for your cooperation. 

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