Re: [Mimedefang] long dns timeouts when first dns in /etc/resolv.conf is down
Hi there, On Mon, 14 Mar 2016, Marcus Schopen wrote: ... It shouldn't make a difference to mimedefang if one of the dns server is down. Any ideas? Run a nameserver of your own? -- 73, Ged. ___ NOTE: If there is a disclaimer or other legal boilerplate in the above message, it is NULL AND VOID. You may ignore it. Visit http://www.mimedefang.org and http://www.roaringpenguin.com MIMEDefang mailing list MIMEDefang@lists.roaringpenguin.com http://lists.roaringpenguin.com/mailman/listinfo/mimedefang
Re: [Mimedefang] long dns timeouts when first dns in /etc/resolv.conf is down
On Mon, 14 Mar 2016 14:11:38 +0100
Marcus Schopen wrote:
> It shouldn't make a difference to mimedefang if one of
> the dns server is down. Any ideas?
I think this is an artifact of the Net::DNS Perl module, which doesn't
seem to handle multiple name servers very well.
I ran the following test program, where 10.50.100.100 is a nonexistent
machine and 192.168.10.23 is the real name server. Results of strace are
shown below; it seems by default that Net::DNS only moves to the next name
server after 10s. If you do lots of DNS lookups, that can really
slow things down.
Regards,
Dianne.
#!/usr/bin/perl
ns.pl test program
use Net::DNS;
use Net::DNS::Resolver;
my $r = Net::DNS::Resolver->new(nameservers => ['10.50.100.100',
'192.168.10.23']);
my $x = $r->query('colo3.roaringpenguin.com', 'A');
-
strace output:
$ strace -t -esendto perl ns.pl
10:03:49 sendto(4, "N\341\1\0\0\1\0\0\0\0\0\0\5colo3\16roaringpengui"..., 42,
0, {sa_family=AF_INET, sin_port=htons(53),
sin_addr=inet_addr("10.50.100.100")}, 16) = 42
10:03:59 sendto(4, "N\341\1\0\0\1\0\0\0\0\0\0\5colo3\16roaringpengui"..., 42,
0, {sa_family=AF_INET, sin_port=htons(53),
sin_addr=inet_addr("192.168.10.23")}, 16) = 42
10:03:59 +++ exited with 0 +++
___
NOTE: If there is a disclaimer or other legal boilerplate in the above
message, it is NULL AND VOID. You may ignore it.
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[Mimedefang] long dns timeouts when first dns in /etc/resolv.conf is down
Hi, I had a strange behaviour this weekend: the first of two dns server of my hoster in /etc/resolv.conf was down. The second dns server was working. Mimedefang/Spamassassin didn't like that. I had very long dns time outs for remote checks. It took over a minute for an email to run through mimedefang. System wide dns worked fine, eg. like pinging domains. After removing the "down" dns server from /etc/resolv.conf and restarting sendmail and mimedefang emails went through within a second again. It shouldn't make a difference to mimedefang if one of the dns server is down. Any ideas? Ciao Marcus ___ NOTE: If there is a disclaimer or other legal boilerplate in the above message, it is NULL AND VOID. You may ignore it. Visit http://www.mimedefang.org and http://www.roaringpenguin.com MIMEDefang mailing list MIMEDefang@lists.roaringpenguin.com http://lists.roaringpenguin.com/mailman/listinfo/mimedefang
