Has anyone ever noticed that EM can tend to be a rather abusive DNS client
app? I have defined aliases for the IP addresses using cliconfg for all
servers that are registered in EM. None of the aliases use DNS names. All
of the servers but 1 are connected and I can access them from EM.
This all sounds like a non-issue, except that for one of the servers, EM is
querying DNS every 2 seconds! It's trying to resolve an alias with my
system's DNS suffix appended.
At one point I had 5 of them doing it (they take turns) so I created
[essentially bogus, though correctly resolvable] DNS entries for each of
them so the DNS queries they were generating would be resolvable. My theory
was that if it got workable answers to it's ill-founded questions, it would
mellow-out. It did for all but two.
One of them needs a VPN connection, so I unregistered it from EM -- of
course, querying DNS every 2 seconds does nothing to help a connection that
isn't present, but I figured what the hell, it sees it's not connected, so
for it to be all worked up about it is somewhat understandable.
That leaves one freakin rogue... it's connection is working perfectly...
sometimes it slacks a bit and allows 5 seconds to pass between DNS queries
but it's still a more-or-less constant stream of traffic. Making it so the
queries artificially resolve did change its behavior a little, but it's
still way excessive, imho.
So where am I going with this? I swear I had a direction when I started...
Why does EM attempt to use DNS, when the names have already been resolved
using its own proprietary mechanism (cliconfg)?
Why does it continue to issue DNS queries after it's already connected --
it's got the address and has an active connection, even if the DNS failed to
resolve, why continue to look it up (as if it's likely to change anytime
What possible good reason could it have to poll DNS so frequently? What's
the value of repeating the same query over and over? If DNS resolved to a
different address would it switch? That'd suck!
Long story short, an even remotely plausible reason defies my imagination.
If you're wondering what I'm doing that makes this little trait a source of
irritation, I'm working on an app that analyzes DNS log output. It was easy
enough to filter the noise data from my working sets, so there's no real
issue, other than I'd like to know if there's a good reason for this
seemingly insane waste of resources.