desktop-packages team mailing list archive

[Stéphane Graber <stgraber@xxxxxxxxxxxx>]

Public bug reported:

When using dnsmasq as a backend, Network Manager currently passes
--strict-order.

This is a good way to get a similar behaviour to that of the libc's
resolver where the DNS servers are being queried sequentially with a
2-3s timeout per server. However in the case where the first DNS server
is down, this will delay all the DNS queries on the system.

Instead, I recommend this parameter be dropped which will fallback to
the default dnsmasq mode to send the initial request to all servers and
then continue with the first one that replies. This will increase the
load on the upstream DNS servers quite a bit (though not as much as
using --all-servers) but will ensure a proper fallback when some servers
are down or very slow.


I think this added load is reasonable and shouldn't affect most DNS servers too much. For cases where it's a concern (heavily loaded corporate network for example), I'd suggest the user simply turns off the dnsmasq plugin in /etc/NetworkManager/NetworkManager.conf thereby reverting to the libc's behaviour of trying servers sequentially with a 3s timeout.

** Affects: network-manager (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/903854

Title:
  Change default dnsmasq flags to not includ --strict-order

Status in “network-manager” package in Ubuntu:
  New

Bug description:
  When using dnsmasq as a backend, Network Manager currently passes
  --strict-order.

  This is a good way to get a similar behaviour to that of the libc's
  resolver where the DNS servers are being queried sequentially with a
  2-3s timeout per server. However in the case where the first DNS
  server is down, this will delay all the DNS queries on the system.

  Instead, I recommend this parameter be dropped which will fallback to
  the default dnsmasq mode to send the initial request to all servers
  and then continue with the first one that replies. This will increase
  the load on the upstream DNS servers quite a bit (though not as much
  as using --all-servers) but will ensure a proper fallback when some
  servers are down or very slow.

  
  I think this added load is reasonable and shouldn't affect most DNS servers too much. For cases where it's a concern (heavily loaded corporate network for example), I'd suggest the user simply turns off the dnsmasq plugin in /etc/NetworkManager/NetworkManager.conf thereby reverting to the libc's behaviour of trying servers sequentially with a 3s timeout.

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