Reliability fixes

- Prevent hang on start related to DNSSEC

- Timeout unavailable severs more quickly, which works around transient
  failures (previously wouldn't query a "dead" server for 900s)

- Limit TTL on NXDOMAIN responses

- Fixes for galaxy and linting

Change-Id: I95bf71ec2841e4036a6a14501e9ed285d5249732
diff --git a/files/default_unbound b/files/default_unbound
new file mode 100644
index 0000000..083c07e
--- /dev/null
+++ b/files/default_unbound
@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: 2021 Open Networking Foundation <support@opennetworking.org>
+# SPDX-License-Identifier: Apache-2.0
+
+ROOT_TRUST_ANCHOR_UPDATE="false"