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<DIV><FONT face=Arial size=2>But, technically, isn't dnsmasq the "client" to the
upstream DNS servers? Don't YOU have control over how long you wait for a
reply? Couldn't we have a config-param, similar to how I envisioned this
resolv option would work, where if dnsmasq has multiple upstream nameserver's,
we could specify the timeout for a reply in ms or seconds? This isn't for
a "no such domain", this is for a no-reply (host is down or DNS is not
responding on that host, etc.).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>If you did that, we could even have an option to
send the request to all (or some fraction) upstream servers in parallel and just
take the first reply. I don't know if they'd call us a bad Inet citizen if
we did that, though. But, hey, we're making-up for it by caching the
reply, right? ;)</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>-AJ</FONT></DIV>
<DIV> </DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=simon@thekelleys.org.uk href="mailto:simon@thekelleys.org.uk">Simon
Kelley</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=aweber@comcast.net
href="mailto:aweber@comcast.net">AJ Weber</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Cc:</B> <A
title=dnsmasq-discuss@lists.thekelleys.org.uk
href="mailto:dnsmasq-discuss@lists.thekelleys.org.uk">dnsmasq-discuss@lists.thekelleys.org.uk</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, February 06, 2007 4:34
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: resolver options</DIV>
<DIV><BR></DIV>AJ Weber wrote:<BR>> <BR>> Thank you for your quick
reply...<BR>> <BR>> RE: "options in the custom resolver file",
should we have the ability to <BR>> propagate some of these options?
For example, timeout, attempts and <BR>> rotate? I think they could
be useful in certain situations (like my <BR>> own...I don't want to have
to update all my clients resolv interaction <BR>> -- or can this be set
with a dhcp option of sorts?).<BR><BR>It's not really possible: don't forget
that all this is happening via <BR>UDP: a client sends a request which is a
UDP packet, and gets back an <BR>answer (another UDP packet) or times out. If,
for instance, the client <BR>timeout is 10 seconds, and the dnsmasq one 5,
dnsmasq has no way to tell <BR>the client to give up after 5 seconds except by
returning "no such <BR>domain", which is a lie and could cause all sort of
problems if the <BR>client really believes it. Really the only way is to
adjust the timeout <BR>at the client end.<BR><BR>"rotate" is normally
irrelevant when the client only has one nameserver <BR>- dnsmasq, and
"attempts" should be at least 2 (the default). dnsmasq <BR>has quite complex
methods for chosing between multiple upstream servers <BR>which somewhat
depend on clients retrying at least once.<BR><BR>> <BR>> RE: The
existing leases...I knew the leases were cached in a file, but I <BR>>
didn't know that when dnsmasq starts it actually reads the file and <BR>>
leverages that information. Is that documented somewhere?<BR>>
<BR>I think it's just assumed that that's the function of that file - a
<BR>persistent lease database which survives dnsmasq restarts and
reboots.<BR><BR>As an aside, things work pretty well even without the
persistent <BR>database. If the ratio of available addresses to clients is
reasonably <BR>high then clients will always get given the same address
anyway. The <BR>main problem is that the client name disappears from DNS after
a restart <BR>until the client renews its lease.<BR><BR>> I've said
it before, and I'll say it again: This is a fantastic piece <BR>> of
software!<BR>*blush*<BR><BR>> <BR>> Thanks again,<BR>>
AJ<BR>> <BR>Cheers,<BR><BR>Simon.<BR><BR>>
<BR>> ----- Original Message
-----<BR>> *From:* Simon Kelley <<A
href="mailto:simon@thekelleys.org.uk">mailto:simon@thekelleys.org.uk</A>><BR>>
*To:* AJ Weber <<A
href="mailto:aweber@comcast.net">mailto:aweber@comcast.net</A>><BR>>
*Cc:* <A
href="mailto:dnsmasq-discuss@lists.thekelleys.org.uk">dnsmasq-discuss@lists.thekelleys.org.uk</A><BR>>
<<A
href="mailto:dnsmasq-discuss@lists.thekelleys.org.uk">mailto:dnsmasq-discuss@lists.thekelleys.org.uk</A>><BR>>
*Sent:* Tuesday, February 06, 2007 12:42 PM<BR>>
*Subject:* Re: resolver options<BR>> <BR>> AJ
Weber wrote:<BR>>
><BR>> > If I use a "different"
resolv.conf file (i.e. I use a<BR>> >
resolv-file=/etc/resolv.dnsmasq), will an "option" have the
same<BR>>
effect<BR>> > it normally
would?<BR>> >
<BR>> > For example, I'm considering
changing timeout to 2 (instead of the<BR>>
> default of 5), because I've had some issues with my ISP's
DNS<BR>>
servers<BR>> > recently and don't want to
wait too long for the timeout. With
the<BR>> > broadband connection, any of
the nameservers in my list consistenly<BR>>
> returns in < 1 sec (when they're up, of
course).<BR>> >
<BR>> > Will this have the desired
effect? Any comments or concerns with<BR>>
that<BR>> > change in general? Am I
misunderstanding the purpose of the<BR>>
"options<BR>> > timeout:" ?<BR>>
<BR>> The only lines which are read by dnsmasq are
"nameserver" ones -<BR>> everything else is
ignored, except "search" if the option --domain=#
id<BR>> used, when the first entry of the search
string is used as dnsmasq's<BR>> domain
setting.<BR>> <BR>> To get the effect of faster
time-outs, it's necessary to alter the<BR>> timeout
in the clients, not in dnsmasq.<BR>> >
<BR>> > ALSO...(DIFFERENT TOPIC) : Is
there no way to tell dnsmasq to<BR>> dump
it's<BR>> > current lease-info to a file
that could be read on restart so it<BR>>
knows<BR>> > about all outstanding DHCP
leases? It's rare that I have to
restart<BR>> > dnsmasq or the linux box
it's on, but when I do, it forces me to<BR>>
restart<BR>> > a lot of client machines in
case I'd get a dhcp/IP address mix-up<BR>>
(where<BR>> > dnsmasq doesn't know an IP
Address is already leased to a running<BR>>
> client, and a new client requests a lease so it hands-out the
same<BR>> > address).<BR>>
<BR>> Dnsmasq does this by default, in
/var/lib/misc/dnsmasq.leases. You can<BR>> change
the location of the lease file using --dhcp-leasefile.<BR>>
<BR>> Cheers,<BR>>
<BR>> Simon.<BR>>
<BR>> >
<BR>> > Thanks in
advance,<BR>> >
AJ<BR></BLOCKQUOTE></BODY></HTML>