For setting a specific DNS server for your pod, you can use the following:

kubectl patch deployment server -n myapp \
  --type=json \
  -p='[
    {
      "op": "add",
      "path": "/spec/template/spec/dnsPolicy",
      "value": "None"
    },
    {
      "op": "add",
      "path": "/spec/template/spec/dnsConfig",
      "value": {
        "nameservers": , 
        "searches": 
      }
    }
  ]'

For setting specific host aliases, you can use the following:

kubectl patch deployment server -n myapp \
  --type=json \
  -p='[
    {
      "op": "add",
      "path": "/spec/template/spec/hostAliases",
      "value": [
        {
          "ip": "<ip of server>",
          "hostnames": 
        }
      ]
    }
  ]'

You can check and see if your deployment was updated correctly:

kubectl get deployment server -n myapp -o yaml | grep -A 5 dnsConfig
kubectl get deployment server -n myapp -o yaml | grep -A 5 hostAliases

If you need to roll back your DNS changes, you can use this:

kubectl patch deploymentserver -n myapp \
  --type=json \
  -p=''

Well, there you have it. A simple way to add a custom DNS server configuration or host aliases to specific pods. Pretty cool