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ID Category Severity Reproducibility Date Submitted Last Update
0000889 [ClarkConnect] Caching DNS Server minor always 2008-06-05 20:01 2008-07-14 15:56
Reporter paul_va3pc View Status public  
Assigned To peter
Priority normal Resolution fixed  
Status closed   Product Version 4.2
Summary 0000889: DHCP assigned DNS servers. If first DNS lookup fails, it does not seem to check the rest.
Description I have a DHCP assigned WAN IP (with DNS servers etc.)
When the first listed DNS server doesn't respond, it appears that the no. 2 and no. 3 servers are not checked - they just show failed.
I was able to confirm it tonight - the DNS lookups were very slow, and when I opened webconfig IP settings, it showed all three DNS servers as down.
When I exchanged no. 1 and no. 3 DNS addresses, and updated the settings, no. 1 and no. 2 now show working, and no. 3 shows failed (the old no. 1).
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-  Notes
(0000837)
paul_va3pc (reporter)
2008-06-09 10:44

It appears that the bug system takes the number sign as a shortcut to an existing bug report. Please do not take the hyperlinks literally, and just refer the numbers to the DNS servers as listed in the webconfig page.
(0000838)
peter (administrator)
2008-06-09 11:33

You will see that behavior when a DNS server is responding, but responding with "DNS record does not exist". There's no need to check DNS no.2 and no.3 if the first one responded. There are two common causes:

1) The upstream DNS server is broken.

2) The upstream DNS server is an authoritative server, not a caching/forwarding server. Only use DNS servers provided by your ISP (or some other caching service). Using something like ns1.pointclark.net (an authoritative DNS server) is... bad.

Hmmmm... the warning on the IP settings page should really read something like "DNS did not return information" instead of "DNS server is not responding". There's a subtle difference.
(0000839)
paul_va3pc (reporter)
2008-06-09 13:30

I agree - the upstream DNS server is sometimes broken ;-)
These are the DNS's from my ISP (as given by DHCP on wan).
Whenever things bog down, I change the non-responsive DNS to an openDNS address and after restarting services, things are OK until my network restarts.

- Issue History
Date Modified Username Field Change
2008-06-05 20:01 paul_va3pc New Issue
2008-06-09 10:44 paul_va3pc Note Added: 0000837
2008-06-09 11:33 peter Note Added: 0000838
2008-06-09 11:34 peter Status new => feedback
2008-06-09 11:54 peter Description Updated
2008-06-09 13:30 paul_va3pc Note Added: 0000839
2008-07-14 15:47 peter Status feedback => resolved
2008-07-14 15:47 peter Fixed in Version => 4.3
2008-07-14 15:47 peter Resolution open => fixed
2008-07-14 15:47 peter Assigned To => peter
2008-07-14 15:56 peter Status resolved => closed

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