[Dnsmasq-discuss] Dealing with a unstable/slow upstream DNS

Joachim Berdal Haga jobh at simula.no
Fri Oct 4 08:56:49 BST 2013


I have tried to use dnsmasq on a compute cluster where the DNS is
occasionally very slow. I was hoping to avoid the administration of a large
host file on every node. But I have not been able to mask the problems

1) I can maintain /etc/hosts on the master node, but the worker nodes will
still query, and wait for, for AAAA records. The problem is compounded by
the negative-lookup TTL being rather short. Is it possible to instruct
dnsmasq to not forward AAAA requests when the A record is deduced from
/etc/hosts (or vice versa)?

2) For cached entries (not in /etc/hosts), there is still the occasional
hang when the entry expires. Which, as mentioned, happens fairly frequently
for negative lookups. Is it possible to instruct dnsmasq to refresh its
cache while replying immediately with the already cached record? Either
optimistically (when the entry will soon expire) or lazily (when the entry
has just expired).

I have looked hard at the documentation, and so I guess that the answer to
these questions is no :-) But still worth asking. And maybe there are other
ways to deal with it?

Joachim B Haga
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