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Can anyone tell me a quick way to test cluster-dns...
# rke2
e
Can anyone tell me a quick way to test cluster-dns mappings? I have a pod trying to build up, but when it reaches out to core-dns on udp/53 it times out.
c
what do you mean by ‘mappings’
e
so it's trying to go to istiod.istio-system.svc, not a "real" external name.
c
e
if I jump in the rke2-coredns-rke2-coredns-# pod shell and try and nslookup, it just sends it out to normal DNS.
c
yes, because the coredns pod is what talks to other things
pods using cluster dns talk to coredns. coredns serves kubernetes records for the cluster domain, and forwards lookups for stuff outside the cluster domain
that is how dns works in kubernetes
e
Would that vmware bug also impact calico CNI?
c
it affects anything that uses vxlan as the cluster overlay. it is not cni specific.
since it is a bug in the kernel
e
Something new? We've had this running for 9 months with no sign of trouble until now.
c
sometimes people don’t notice until they happen to not have a replica of the coredns pod running on the same node as something else
idk. are you on vmware?
e
VMware ESXi7 with RHEL8 VM's
c
well then I’d definitely try that fix.
e
Just wondering what I have to modify since that example was for flannel
c
if you look at other comments in that issue there is a link to an issue in the calico repo with more info
👍 1
e
Thanks for the quick response @creamy-pencil-82913! I have a ticket with Rancher open.
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