[Dnsmasq-discuss] Multiple upstream servers
simon at thekelleys.org.uk
Wed Mar 14 20:57:54 GMT 2007
Jay Guerette wrote:
> I was surprised; and expecting a load balancing of the 3 configured
> servers. The man entry for the 'strict-order' option says:
> "... dnsmasq will send queries to any of the upstream servers it knows
> about and tries to favour servers to are known to be up..."
> I interpreted this to mean it would use all the servers that are up,
> and tune the load on each in the pool based on it's response times.
There's a trade-off here with complexity, load-balancing and robustness.
The existing algorithm tries hard to be simple and not to send a query
to just one server unless it's known to be up. It therefore copes well
with a list of servers, some of which are dead, without accidentally
loosing queries or causing long time-outs. To do better load balancing,
it would either cope less well with dead servers, or need more complex
and longer-lasting state about each query.
> Specifically the words "favour servers", lead me to believe it would
> use more than one. I interpreted the use of the 'strict-order' option
> was to strictly round-robin, with no attention paid to response times.
> Now I know, this is the expected behaviour. Thank you for your reply.
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