dnsmasq --server flags causing upstream name server calls to hang and time out sporadically about dns

[bowei]

In 1.6, dnsmasq will only forward requests that pertain to cluster.local (and reverse record lookups) to kube-dns. All other requests will go out directly to the upstream resolver.

Can you post your /etc/resolv.conf from the container?

[michaelajr]

Sorry I did not see this sooner. The etc resolv.conf in the dnsmasq container is the same as the host's

nameserver 10.236.129.75
nameserver 10.236.129.85

These are our VPC name servers. They resolve fine from the host and inside the dnsmasq container. This is what I get from an nslookup inside the dnsmasq container:

$ nslookup www.google.com
nslookup: can't resolve '(null)': Name does not resolve

Name: www.google.com
Address 1: 172.217.5.228 iad30s07-in-f4.1e100.net
Address 2: 2607:f8b0:4004:804::2004 iad30s07-in-x04.1e100.net

(although I am not sure why IPv6 is returned)

And upstream forwarding seems to work when there is only one --server flag in the dnsmasq config as outlined in the OP.

[bowei]

That nslookup looks to be correct -- the first (null) is a the result of a reverse lookup for the nameserver itself.

Is it possible to tcpdump -i any -n port 53 on the kube-dns pod node to see what packets are being sent?

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[bowei]

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