On 02/14/2011 01:57 PM, Scott Hughes wrote:
I use a caching name server on my QMT server. Here is what I have in my
/etc/resolv.conf file:
nameserver 127.0.0.1
nameserver 4.2.2.3
nameserver 4.2.2.4
This way if it does not resolve it locally, it will resolve it using one
of the other DNS servers listed. Once it is resolved once, my local
server will hold onto it for a period of time so that future look-ups
will be faster.
I don't believe that's quite right, Scott. I believe it will only cache
hits that are satisfied by the localhost (127.0.0.1) resolver. I think
it would be better to specify forwarders in the named.conf file. Then,
indeed, hits from alternate resolvers would be cached.
This is what I have in my named.conf:
//
// named.conf
//
options {
forward first;
forwarders {
205.171.3.25;
208.67.222.220;
205.171.2.25;
208.67.222.222;
};
};
logging {
category lame-servers { null; };
};
These IPs are for my ISP (Qwest) and OpenDNS. I think that by specifying
forwarders, it relieves some stress on the root name servers, which is a
good thing.
Martin, am I off base on this? I could be.
Hope this helps.
Scott
On Mon, Feb 14, 2011 at 1:58 PM, Eric Shubert <[email protected]
<mailto:[email protected]>> wrote:
Hey Marek,
Using Bind is fine, but using a single server/process for both
authoritative and resolver purposes is not a good practice. It can
be done, but I would try very hard to keep them separate before
endeavoring to put them together. It can be done, but it's a bit
tricky to do well (accurately and securely).
If at all possible, I would use an authoritative DNS server that's
external to QMT, then simply install the caching-nameserver package
on QMT to use as a resolver. You should also modify the resolver's
configuration to use forwarders, but that's not absolutely
necessary. caching-nameserver configuration should work ok as is.
Martin, do you have anything to add? (Sorry for jumping in again)
--
-Eric 'shubes'
On 02/14/2011 12:14 PM, [email protected] <mailto:[email protected]> wrote:
Thank You for advice.
I think, I must learn about DNS much more as I thought before i
wrote
these emails.
I'm using BIND (named).
Yes it's authoritative DNS server and i think it's a local
resolver. Now
I understand it's wrong practice?
Now i'm going to try apply you advices and read something more
about DNS
server.
I will let you know about my progress
regards
Marek
----- Original Message ----- From: "Eric Shubert"
<[email protected] <mailto:[email protected]>>
To: <[email protected]
<mailto:[email protected]>>
Sent: Monday, February 14, 2011 4:24 PM
Subject: [qmailtoaster] Re: DNS temporary failure if one DNS
server dont
work.
I agree whole heartedly with Martin (whatever that's worth).
Two key questions which haven't been answered yet by Marek:
1) which software is he using (bind or djbdns)
2) is he using the local resolver as an authoritative DNS
server as
well? (I would hope not, but you never know).
I gotta chuckle regarding Marek's name, as there is a
commercial email
server called "Marek Mail". :)
Thanks, Martin. I'll let you finish up with this one.
--
-Eric 'shubes'
On 02/14/2011 01:39 AM, Martin Waschbüsch wrote:
Seeing as it does not work right now, I don't know where
the servers
are listed on his system. Clearly there must be some
configuration
issue.
But at the same time, IMHO it is the best solution to
ensure there is
a properly configured local DNS server.
Such a local DNS server has a config where you can list
forwarding
DNS servers and that is where his name servers should be
configured.
Imagine resolv.conf lists the two outside DNS servers
directly.
Let's assume that the first entry (will be queried
first) is down.
Although the system tries to send 50 individual mails to
[email protected] <mailto:[email protected]>,
the mail server will experience a timeout for
the first name server and only then query the secondary
server. All
that happens 50 times(!)
Now, if you have a working caching DNS server, as soon
as the first
timeout happened and the secondary DNS server was
queried, the local
server has the DNS entry stored and the remaining 49
messages do not
encounter any timeout at all.
Martin
--
Martin Waschbüsch
IT-Dienstleistungen
Lautensackstr. 16
80687 München
Telefon: +49 89 57005708
Fax: +49 89 57868023
Mobil: +49 170 2189794
[email protected] <mailto:[email protected]>
http://martin.waschbuesch.de
Am 14.02.2011 um 09:06 schrieb Tony White:
Hi,
So what/where are the two dns servers Marek
says he is using?
On 14/02/2011 7:02 PM, Martin Waschbüsch wrote:
That is not correct!
If localhost runs a caching DNS server, it will
fetch DNS
information from forwarding DNS servers, which
can be the ISP's,
Google's, whatever.
The whole point of having a local caching DNS
server is that it not
only takes care of using all DNS servers it
knows about to fetch
data, but also to store that data and prevent
DNS-lookup-heavy
applications (like E-Mail servers) to generate
lots of additional
traffic and overhead.
So, if Marek runs a local DNS server and still
gets problems, then
we need to look at that config.
If not, he really should install a caching DNS
server (named,
djbdns, etc.)
In any case, resolv.conf is just fine only
pointing to the local
server.
Martin
--
Martin Waschbüsch
IT-Dienstleistungen
Lautensackstr. 16
80687 München
Telefon: +49 89 57005708
Fax: +49 89 57868023
Mobil: +49 170 2189794
[email protected] <mailto:[email protected]>
http://martin.waschbuesch.de
Am 14.02.2011 um 07:59 schrieb Bruno De Leone:
That means your only DNS is your local DNS
so the qmail will never
find any server outside it's network...
You should add the DNS of your preference.
For example, to add
google's DNS, edit the file /etc/resolv.conf
and add these lines
at the end of the file:
nameserver 8.8.8.8
nameserver 4.4.4.4
On Mon, Feb 14, 2011 at 4:39 AM,<[email protected]
<mailto:[email protected]>> wrote:
In resolv.conf I have only:
"search localdomain
nameserver 127.0.0.1"
----- Original Message ----- From: "Tony
White"<[email protected] <mailto:[email protected]>>
To:<[email protected]
<mailto:[email protected]>>
Sent: Monday, February 14, 2011 2:55 AM
Subject: Re: [qmailtoaster] DNS temporary
failure if one DNS
server dont work.
Marek,
What order are the dns servers in
/etc/resolv.conf?
If they are the failing one on line one then
reverse them.
On 14/02/2011 9:03 AM, [email protected]
<mailto:[email protected]> wrote:
Thanks for fast reply.
I use 2 named servers.
everyone in different locations. One DNS
server is on the same
machine as qmailtoaster and always on. But
when secondary DNS on
the other location die i canot send email
outside.
----- Original Message ----- From: "Carlos
Herrera
Polo"<[email protected]
<mailto:[email protected]>>
To:<[email protected]
<mailto:[email protected]>>
Sent: Sunday, February 13, 2011 10:02 PM
Subject: Re: [qmailtoaster] DNS temporary
failure if one DNS
server dont work.
Djbdns or named
2011/2/13, Martin
Waschbüsch<[email protected]
<mailto:[email protected]>>:
What you could try is this:
Have a local caching DNS server and that
takes care of resolving
to as many
'real' DNS servers as you like.
Doing so means that your DNS server (local)
is ALWAYS on (unless
the daemon
dies) and this problem won't occur again.
Martin
--
Martin Waschbüsch
IT-Dienstleistungen
Lautensackstr. 16
80687 München
Telefon: +49 89 57005708
Fax: +49 89 57868023
Mobil: +49 170 2189794
[email protected]
<mailto:[email protected]>
http://martin.waschbuesch.de
Am 13.02.2011 um 19:48 schrieb<[email protected]
<mailto:[email protected]>> <[email protected]
<mailto:[email protected]>>:
Hello everyone
I have a problem with my qmailtoster. When
one of my DNS server is
down i
cant send email. When i try send email
outside i have an error
message:
DNS temporary failure. This hapen even if
one DNS server works
correctly.
Does anyone know how can I solve it?
Thanx for you help.
Marek
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Wiadomosc zostala sprawdzona przez program
ESET NOD32 Antivirus.
http://www.eset.pl lub http://www.eset.com
__________ Informacja programu ESET NOD32
Antivirus, wersja bazy
sygnatur wirusow 5835 (20110131) __________
Wiadomosc zostala sprawdzona przez program
ESET NOD32 Antivirus.
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Qmailtoaster is sponsored by Vickers
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sygnatur wirusow 5835 (20110131) __________
Wiadomosc zostala sprawdzona przez program ESET NOD32 Antivirus.
http://www.eset.pl lub http://www.eset.com
---------------------------------------------------------------------------------
Qmailtoaster is sponsored by Vickers Consulting Group
(www.vickersconsulting.com <http://www.vickersconsulting.com>)
Vickers Consulting Group offers Qmailtoaster support and
installations.
If you need professional help with your setup, contact them today!
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Vickers Consulting Group offers Qmailtoaster support and
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