[Xymon] DNS test interaction with 0.0.0.0

[John Thurston]

I have a couple of name servers which are not pingable. I have them in 
my hosts.cfg as follows:

> 10.10.10.10   ns1-int.foo.com      # noconn dns=ns1.foo.com
> 0.0.0.0       ns2-int.foo.com      # noconn dns=ns2.foo.com

The first returns a green dns test result. The second returns a red 
"Service dns on ns2-int.foo.com is not OK : Service unavailable."  I 
can't figure out why. I don't want to embed ip addresses in my 
hosts.cfg, and I can't think why I should need to.


There is nothing telling when I run the test interactively with:
   xymoncmd xymonnet --no-update --debug  ns1-int.foo.com
nor for ns2-int.foo.com


When I snoop the interface while doing the above tests, the differences 
are significant:

For ns1-int, I see xymon lookup ns1-int on the normal name server.
Then I also see it request ns1.foo.com from ns1-int.foo.com and get the 
correct response. I'm not sure why the reverse lookup is there.
>       xymona -> d.foo.com DNS C ns1-int.foo.com. Internet Addr ?
> d.foo.com -> xymona       DNS R ns1-int.foo.com. Internet Addr 10.10.10.10
>       xymona -> ns1-int.foo.com DNS C ns1.foo.com. Internet Addr ?
> ns1-int.foo.com -> xymona       DNS R ns1.foo.com. Internet Addr 192.168.123.1
>       xymona -> d.foo.com DNS C 10.10.10.10.in-addr.arpa. Internet PTR ?
> d.foo.com -> xymona       DNS R 10.10.10.10.in-addr.arpa. Internet PTR ns1-int.foo.com.


For ns2-int, however, the result is much simpler. I see xymon lookup 
ns2-int on the normal name server. . . . and then nothing.
>       xymona -> d.foo.com DNS C ns2-int.foo.com. Internet Addr ?
> d.foo.com -> xymona       DNS R ns2-int.foo.com. Internet Addr 10.20.20.20


When I change the line in hosts.cfg for ns2-int from 0.0.0.0 to an ip 
address, it works fine.

What is going on here? Why isn't the DNS test using the address it has 
obviously retrieved from DNS?
-- 
    Do things because you should, not just because you can.

John Thurston    907-465-8591
John.Thurston at alaska.gov
Enterprise Technology Services
Department of Administration
State of Alaska