I am on 152 and have been experiencing similar wobbly DNS for months now. In the following I identify an exact time frame when these things started on my machine, as well as what looks like a parsing error.
What caught my eyes was the statement in post #27 about spaces. Years (sigh, decades) ago I ran into a problem with a file parser that died when one used spaces instead of tabs in /etc/hosts. So I decided to check.
I logged in on my IPFire box and typed grep " " /etc/hosts which returned:
127.0.0.1 localhost.localdomain localhost
Replacing the space between localhost.localdomain and localhost with a tab made the name resolution start working again.
FYI: Name resolution stopped working after my router did a soft restart, so that might be a hint to another problem.
So, how bad is it? See for yourself:
[root@ipfire ~]# zgrep -c "all the configured stub or forward servers failed, at zone ." /var/log/messages* \
| awk -F: '{printf $2 "+"}END{print "0"}' \
| bc
121997
That is from 25 Mar to 13 Dec, or 264 days (don’t fall for the fence post error), giving an average of just over 462 log entries per day.
More importantly, it was in the same log file that I started seeing these errors:
DDNSResolveError: Could not resolve DNS entry
but they started on 22 Mar, three days earlier.
My logs on this machine go back to 27 Jan, so I think the above should help.
I am about to go on leave (in the mountains), so won’t have access to the firewall. In fact, it will be switched off while I am gone, so I cannot help any more on this right now.