Author Topic: Couldn't resolve host  (Read 1623 times)

Per E. Johannessen

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Couldn't resolve host
« on: May 05, 2018, 03:44:36 pm »
Hi,

I have a rexx program that automates sending emails with attachments and it has worked perfectly for years.
All of a sudden it is not sending anymore and I found this error message in the log:
cURL error: 6 - Couldn't resolve host 'mail.broadpark.no'

This pc is set up using DNS and and Firefox works OK.

The one who normally uses this pc cannot remember changing anything.
Nothing has changed at the ISP and all login/host details are correct in the setup of the rexx program.

Ideas anyone?

Dariusz Piatkowski

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Re: Couldn't resolve host
« Reply #1 on: May 05, 2018, 08:08:04 pm »
Does it resolve through tracerte?

From my machine, executing 'tracerte mail.broadpark.no' at CLI gives:

Code: [Select]
[G:\]tracerte mail.broadpark.no
traceroute to mail.broadpark.no (80.235.81.36), 30 hops max, 38 byte packets
 1  router                    (192.168.1.1)  0 ms  0 ms  0 ms
 2  10.88.64.1                (10.88.64.1)  10 ms  10 ms  10 ms
 3  225-4-226-24.rev.cgocable.net  (24.226.4.225)  10 ms  30 ms  10 ms
 4  10.0.18.73                (10.0.18.73)  20 ms  10 ms  30 ms
 5  toro-b1-link.telia.net    (213.248.92.105)  20 ms toro-b1-link.telia.net
(213.248.92.221)  20 ms toro-b1-link.telia.net    (80.239.194.193)  20 ms
 6  motl-b1-link.telia.net    (62.115.134.49)  20 ms  30 ms  20 ms
 7  nyk-bb3-link.telia.net    (62.115.137.142)  150 ms  150 ms  150 ms
 8  nyk-b6-link.telia.net     (62.115.125.63)  30 ms kbn-bb3-link.telia.net    (
213.155.134.51)  150 ms  150 ms
 9  s-bb3-link.telia.net      (62.115.139.168)  140 ms  140 ms nyk-bb4-link.teli
a.net    (80.91.254.37)  130 ms
10  kbn-bb4-link.telia.net    (80.91.254.90)  130 ms tln-b3-link.telia.net     (
62.115.134.219)  140 ms tln-b3-link.telia.net     (213.155.133.15)  130 ms
11  s-bb4-link.telia.net      (62.115.139.172)  130 ms  140 ms  130 ms
12  90.190.134.25             (90.190.134.25)  140 ms 90.190.134.163
(90.190.134.163)  140 ms 90.190.134.25             (90.190.134.25)  130 ms
13  * elion-ic-302547-tln-b3.c.telia.net  (62.115.34.134)  140 ms *
14  90.190.134.163            (90.190.134.163)  140 ms * *
15  * * *
16  * * *
17  *

...so I killed it at #17 as it was not resolving...but the IP address does come back, while 'ping mail.broadpark.no' does not.

Dave Yeo

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Re: Couldn't resolve host
« Reply #2 on: May 05, 2018, 08:34:25 pm »
There's also the chance that something has changed in between you and the server. On eCS the size of MTU can be a factor

Per E. Johannessen

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Re: Couldn't resolve host
« Reply #3 on: May 06, 2018, 02:49:00 pm »
This is the result of tracerte:

traceroute to mail.broadpark.no (80.235.81.36), 30 hops max, 38 byte packets
1 10.0.0.1            (10.0.0.1) 0 ms 0 ms 0 ms   
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *
7 * * *

I believe that the user of this pc has accidentally changed something. To change MTU size, isn't that done
via command prompt? Doubt that this user has changed anything that is not easily changed from the WPS.


ivan

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Re: Couldn't resolve host
« Reply #4 on: May 06, 2018, 03:24:58 pm »
Is that machine actually on the 10.0.0.0/16 network?

Does it get its IP address from a DHCP server or does it have a fixed IP?

If it is a fixed IP is that IP allowed through the router/modem?

Those are the sort of questions you should be asking.  I have seen the sort of mess someone made when they started playing about with the TCPCONFIG gui, there are also things that can mess up a system network in the Connections/Network folder.

Per E. Johannessen

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Re: Couldn't resolve host
« Reply #5 on: May 06, 2018, 08:27:51 pm »
No fixed IP, using DHCP.

ivan

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Re: Couldn't resolve host
« Reply #6 on: May 06, 2018, 08:38:25 pm »
OK, what is the DHCP range, and what is the DHCP server?

It might be that the machine has somehow ended up with an IP address that is outside the DHCP range and so anything is not passed through to the outside world.  For example here the DHCP range is 192.168.0.10 to 192.168.0.60 and anything outside that range is blocked by the modem firewall on both outgoing and incoming, that way the network printers and managed switch are not accessible from the internet.