[Xymon] what IS the "DNS" check in xymon?

[Jeremy Laidman]

The dns/dig test is essentially doing "dig @<hostname> <hostname>" or
"dig @<hostname> <type> <lookup>" (when using the "dns=type:lookup" form),
for each entry in the comma-separated dig=..,..,.. list. If the requests
all return valid results (NOERROR status, and one or more answer records),
the status is green. Xymon also times how long all of the lookups take to
complete, so that a graph of response times can be displayed.

Yes AAAA works. The query type is matched against a lookup list defined as
per below (from xymonnet/dns2.c). This includes AAAA. Not all valid record
types are supported, but the DNS test isn't really supposed to be
exercising a range of record types, just testing that the DNS server can
respond to some typical query and give a valid response, so support for all
possible types is not warranted.

Cheers
Jeremy

static const struct nv types[] = {
  { "A",        T_A },
  { "NS",       T_NS },
  { "MD",       T_MD },
  { "MF",       T_MF },
  { "CNAME",    T_CNAME },
  { "SOA",      T_SOA },
  { "MB",       T_MB },
  { "MG",       T_MG },
  { "MR",       T_MR },
  { "NULL",     T_NULL },
  { "WKS",      T_WKS },
  { "PTR",      T_PTR },
  { "HINFO",    T_HINFO },
  { "MINFO",    T_MINFO },
  { "MX",       T_MX },
  { "TXT",      T_TXT },
  { "RP",       T_RP },
  { "AFSDB",    T_AFSDB },
  { "X25",      T_X25 },
  { "ISDN",     T_ISDN },
  { "RT",       T_RT },
  { "NSAP",     T_NSAP },
  { "NSAP_PTR", T_NSAP_PTR },
  { "SIG",      T_SIG },
  { "KEY",      T_KEY },
  { "PX",       T_PX },
  { "GPOS",     T_GPOS },
  { "AAAA",     T_AAAA },
  { "LOC",      T_LOC },
  { "SRV",      T_SRV },
  { "AXFR",     T_AXFR },
  { "MAILB",    T_MAILB },
  { "MAILA",    T_MAILA },
  { "ANY",      T_ANY }
};


On Wed, 16 Feb 2022 at 06:58, Richard L. Hamilton <rlhamil2 at gmail.com>
wrote:

> Would an AAAA lookup also work? I realize that most of Xymon isn't yet
> IPv6 aware, but if one can define a DNS test to use arbitrary types, it
> seems that _ought_ to work.
>
> > On Feb 15, 2022, at 11:28, John Thurston <john.thurston at alaska.gov>
> wrote:
> >
> > 'tis in the man page for hosts.cfg, but I'll paste it here for ready
> reference:
> >
> > *dns*
> >    Simple DNS test. It will attempt to lookup the A record for the
> hostname of the DNS server.
> >
> >
> > Which means the test performed by xymonnet is attempting to look up an
> A-record for the name "walkie" and failing. It is doing something like:
> >
> >   dig +short +notcp A walkie @10.24.38.132
> >
> > Either change your hostname to a fully-qualified domain name (FQDN)
> (e.g. walkie.foo.bar.com), or change your DNS test to use the long-form:
> >
> > *dns=TYPE:lookup[,TYPE:lookup...]*
> >    The default DNS tests will attempt a DNS lookup of the DNS' servers
> own hostname. You can specify the hostname to lookup on a DNS server by
> listing it on each test.
> >
> > That would make the right side of your line look like:
> >   dns=A:walkie.foo.bar.com
> >
> > --
> > Do things because you should, not just because you can.
> >
> > John Thurston    907-465-8591
> > John.Thurston at alaska.gov
> > Department of Administration
> > State of Alaska
> >
> > On 2/14/2022 11:38 PM, Ian Diddams via Xymon wrote:
> >> if we set a hosts.cfg line
> >> 10.24.38.132    walkie # ssh dns
> >> we can expect xymon to check that ssh connections exist for thats
> erver, and also does some sort of dns check.
> >> what exactly IS this check?
> >> becasue the dns on that server is runjning fine - but the xymon alert
> shopws red.
> >
> > _______________________________________________
> > Xymon mailing list
> > Xymon at xymon.com
> > http://lists.xymon.com/mailman/listinfo/xymon
>
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