Problems resolving DNS names in kubernetes environments

Copper Contributor

I am seeing a problem with being able to resolve DNS names from within POD containers on a windows node that has been joined to a kubernetes cluster.  I'm using flannel and the network setup uses host-gw (not vxlan).  Everything was fine until I applied the cumulative update from Sept 2020 to the windows server OS.  After that point, nslookup calls in the containers result in not being able to reach the DNS server over on the kubernetes master.  I have my firewall turned off and cannot see any DNS traffic leaving the windows server environment using wireshark.  When I revert this patch, DNS works just fine.  I am able to reach the internet (if using just IP addrs) so it doesn't appear to be a general networking seems to be specific to DNS lookup.  Others experienced this problem?  Could it related to the "10 year old DNS hole" that was plugged back in a July release of Windows Server?

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