[hobbit] bbtest shows long DNS runtime, why

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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