[Dnsmasq-discuss] Question about --all-servers in man page

[Dominik DL6ER]

Hey Masanari,

On Fri, 2021-09-03 at 19:26 +0900, Masanari Iida wrote:
> dnsmasq-2.85 (Fedora 33, x86_64)
> multiple upstream DNS servers in config file.
> No --strict-order, No --all-server setting .
> 
> Symptom
> Explanation about --all-servers in dnsmasq(8) man page could 
> be different from actual dnsmasq behavior.
> 
> In man page, it is written that 
> "By default, when dnsmasq has more than one upstream server 
> available, it will send queries  to  just one server"
> 
> But actual behavior is, it sends queries to _ALL_ upstream DNS
> servers in config at once.
> And if I set --strict-order in dnsmasq.conf, then it send a query to
> one 
> server at a time.

This is expected behavior, the man page explains this somewhat hidden
in the option --strict-order:

> By default, dnsmasq will send queries to any of the upstream servers
it knows about and tries to favour servers that are known to be up.

This probing of the fastest happens every now and then, to be precise
every 50 queries or every 20 seconds, see
https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=blob;f=src/config.h;h=30e23d8e8fb6a0b78d479f77ea021fe126e0670c;hb=HEAD#l27
and the line below. The default probing could likely be made less
often, but else than that, I don't think there is an inconsistency
here.

Best,
Dominik