On 13/3/19 12:19 am, John Horne wrote:
On Sun, 2019-03-10 at 21:17 +0000, John Horne wrote:
Hi,
Using the 4.3.28 Terabithia RPMs, can someone tell me what the 'dns' test
actually does?
We actually negate the test ('!dns'), and run a client-side dns test ('dnsr')
to check that resolution is working. As far as I remember the standard 'dns'
test checks that the client DNS service can resolve something. This will
always fail in our case as the client DNS service is always restricted to
just the local host. (No querying allowed from an external server.)
I'm trying to work out why most of our servers are taking less than a second
- giving a 'Server unavailable' reply, but others are taking around 20
seconds for a 'Timeout' reply. I know why the timeout is 20 seconds, I'm just
wondering why it's not giving a 'Server unavailable' reply.
Hi,
Thanks for the replies about this.
It seems the network infrastructure in which our monitoring server sits is
blocking ICMP from some networks. Clients in those networks are correctly
sending back an ICMP reject via its local firewall, but these are blocked. So
the Xymon server times out the connection instead. I've asked if ICMP rejects
can be allowed through.
Maybe also refer them to this: http://shouldiblockicmp.com/
ie, don't block all ICMP.... some is required so that the Internet thing
works properly...
Regards,
Adam
--
Adam Goryachev Website Managers www.websitemanagers.com.au
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