RE: [hobbit] bbtest shows long DNS runtime, why

["Hubbard, Greg L" <greg.hubbard (at) eds.com>]

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
host.
 
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.
 
GLH
 
________________________________

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




	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.: +49-40-7920-2593
	
	
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