Slow startup due DNS.

*Title*: *One line description*

*Description*:
Envoy is slow to get ready in my IPv6 cluster.
I install envoy 1.12.2 as a part of a contour environment with the attached manifest.
Envoy is installed as a DaemonSet. Some of the pods can take up to 140s to get ready.
I suspect some kind of race condition during startup. If I add a new initcontainer to the DaemonSet, Sleeping 5 seconds, the issue is not reproducible for me.
I do also have another cluster with only IPv4 addresses, and installing with the manifest I also do not see the issue.
The only things I changed compared to the original contour example is:
- getting rid of the internal security.
- changes in the args for envoy to be ready for v6 use
[contour.txt](https://github.com/envoyproxy/envoy/files/4250831/contour.txt)

*Repro steps*:
kubectl apply -f contour.yaml

kubectl get pods -n projectcontour
NAME READY STATUS RESTARTS AGE
contour-58f47b9d8c-4k664 1/1 Running 0 2m20s
contour-58f47b9d8c-rpkcv 1/1 Running 0 2m20s
envoy-k59m9 0/1 Running 0 2m20s
envoy-n4kw4 1/1 Running 0 2m20s
envoy-vnnq2 1/1 Running 0 2m20s
envoy-xrnr9 0/1 Running 0 2m20s

I can include the debug logs from envoy-k59m9
[envoy.pod.log](https://github.com/envoyproxy/envoy/files/4250850/envoy.pod.log)

envoy.json used as config.
[envoy.config.txt](https://github.com/envoyproxy/envoy/files/4250841/envoy.config.txt)