[Dnsmasq-discuss] Logging and OpenDNS ...

[Simon Kelley]

Clinton Lee Taylor wrote:
> Greetings ...
> 
> 
> First, thanks to Simon and all the other helps of dnsmasq ... Okay, now
> that I have buttered up the developers ... |-)
> 
> Logging, I'm sure Simon will remember me, because I'm always asking about
> logging, seeing that I can never get it to work in deamon mode ...

The next release includes the ability to log direct to  a file, without
using syslog at all: that might help you there.
> 
> We have had some changes in our ADSL network in SA, our monoply Telco has
> gone and changed things, without letting us know, which was a pain for a me
> and having to go and change all the forwarding DNS servers ...
> 
> So, now my questions and ideas ... First, I understand that dnsmasq
> forwards queries to all the forwarding DNS servers and then uses the first
> returned ... Now, with Telkom taking down a DNS server or changing it (
> 196.25.1.1 ) ... So, clients were not able to access alot of the net ...
> 
> Now:
> 1. What errors might I have seen?
> 2. Is it possible to detect these errors and correct for them?
> 3. If one has many DNS forwarders, does this increase internet traffic
> much?

When dnsmasq starts up, it will send the first query to all the
configured servers, and then use the one which replied first. If that
server goes away, the following sequence occurs

1) Query sent to (now dead server) - no response.
2) Client sees no response and times out - retries query.
3) Dnsmasq notices retry and moved back to initial state - retried query
sent to all servers.
4) As long  as at least one server replies, that becomes the new
preferred server, and things continue.

So, as long as you have at least one working server in the server list,
things should continue without a hickup even is some servers go away.
You won't see errors at all. This scheme increases traffic very little,
since most queries are sent to just one server.


> 4. Would using OpenDNS (208.67.222.222, 208.67.220.220) and strick-order be
> better with local DNS servers just a thrid and forward backup?
> 

strict-order disables the mechanism detailed above - it's a bad idea in
general.

Cheers,

Simon.