We have a STRICT_DNS type of a cluster defined in bootstrap config. In one of our test Pods, the membership count of this cluster became zero. This is understandable because the DNS resolution might have resulted in zero hosts. However this remained like this for quite a long time and after killing the container, Envoy is able to successfully resolve the DNS.

I have taken debug logs when Envoy is not able to resolve this. I see the following line

"source/common/network/dns_impl.cc:118] DNS request timed out 4 times",,

And I see these lines repeatedly
"source/common/network/dns_impl.cc:147] Setting DNS resolution timer for 0 milliseconds",,
"source/common/network/dns_impl.cc:147] Setting DNS resolution timer for 0 milliseconds",,
"source/common/network/dns_impl.cc:147] Setting DNS resolution timer for 0 milliseconds",,
"source/common/network/dns_impl.cc:147] Setting DNS resolution timer for 0 milliseconds",,
"source/common/network/dns_impl.cc:147] Setting DNS resolution timer for 0 milliseconds",,
"source/common/network/dns_impl.cc:147] Setting DNS resolution timer for 0 milliseconds",,
"source/common/network/dns_impl.cc:147] Setting DNS resolution timer for 0 milliseconds",,
"source/common/network/dns_impl.cc:147] Setting DNS resolution timer for 22 milliseconds"

So at this point I am not very clear if it is Envoy issue or container DNS issue - as container restart resolved the issue.
Has any one seen similar issues with DNS? and another question is it the DNS resolution timer behaviour correct in the sense it is trying to resolve 0 milliseconds?