Add analyser to check DNS configuration that may conflict with k8s expectations

[banjoh]

Describe the rationale for the suggested feature.

Kubernetes has a known limitation where if the number of configured nameservers exceeds 3, or the number of search domains exceeds 6 on a DNS configuration entry, some of the entries will get truncated. Error logs indicating that records have been truncated will be written in various places in the cluster (kubelet logs, in-cluster logs).

If such a truncation leads to dropping a critical configuration that is required to resolve hosts within a cluster, it could lead to errors in the cluster. It would be good if, with troubleshoot, we would be able to detect this and inform users about a potential configuration conflict.

Describe the feature

Create the following

• A collector that gathers information about such a possible configuration conflict.
• An analyser that reports this issue to users and directs them on how to here where the kubernetes docs describe the problem in detail and provides a possible solution i.e using Expanded DNS Configuration.