stubby -C /etc/stubby.yml -i
[11:54:59.326874] STUBBY: Read config from file /etc/stubby.yml
{
  "all_context":
  {
    "add_warning_for_bad_dns": GETDNS_EXTENSION_FALSE,
    "appdata_dir": <bindata of "/var/tmp/stubby/">,
    "append_name": GETDNS_APPEND_NAME_TO_SINGLE_LABEL_FIRST,
    "dns_transport_list":
    [
      GETDNS_TRANSPORT_TLS
    ],
    "dnssec": GETDNS_EXTENSION_FALSE,
    "dnssec_allowed_skew": 0,
    "dnssec_return_all_statuses": GETDNS_EXTENSION_FALSE,
    "dnssec_return_full_validation_chain": GETDNS_EXTENSION_FALSE,
    "dnssec_return_only_secure": GETDNS_EXTENSION_FALSE,
    "dnssec_return_status": GETDNS_EXTENSION_FALSE,
    "dnssec_return_validation_chain": GETDNS_EXTENSION_FALSE,
    "edns_client_subnet_private": 1,
    "edns_cookies": GETDNS_EXTENSION_FALSE,
    "edns_do_bit": 0,
    "edns_extended_rcode": 0,
    "edns_version": 0,
    "follow_redirects": GETDNS_REDIRECTS_FOLLOW,
    "hosts": <bindata of "/etc/hosts">,
    "idle_timeout": 10000,
    "limit_outstanding_queries": 0,
    "max_backoff_value": 1000,
    "namespaces":
    [
      GETDNS_NAMESPACE_LOCALNAMES,
      GETDNS_NAMESPACE_DNS
    ],
    "resolution_type": GETDNS_RESOLUTION_STUB,
    "resolvconf": <bindata of "/etc/resolv.conf">,
    "return_both_v4_and_v6": GETDNS_EXTENSION_FALSE,
    "return_call_reporting": GETDNS_EXTENSION_FALSE,
    "round_robin_upstreams": 0,
    "specify_class": 1,
    "suffix": [],
    "timeout": 3000,
    "tls_authentication": GETDNS_AUTHENTICATION_REQUIRED,
    "tls_backoff_time": 900,
    "tls_ca_file": <bindata of "/rom/ca-bundle.crt">,
    "tls_cipher_list": <bindata of "EECDH+AESGCM:EECDH+CHACHA20">,
    "tls_ciphersuites": <bindata of "TLS_AES_128_GCM_SHA256:TLS_AES_2"...>,
    "tls_connection_retries": 5,
    "tls_min_version": GETDNS_TLS1_2,
    "tls_query_padding_blocksize": 128,
    "trust_anchors_backoff_time": 2500,
    "trust_anchors_url": <bindata of "http://data.iana.org/root-anchor"...>,
    "trust_anchors_verify_CA": <bindata of 0x2d2d2d2d2d424547494e204345525449...>,
    "trust_anchors_verify_email": <bindata of "dnssec@iana.org">,
    "upstream_recursive_servers":
    [
      {
        "address_data": <bindata for 1.1.1.1>,
        "address_type": <bindata of "IPv4">,
        "tls_auth_name": <bindata of "cloudflare-dns.com">
      },
      {
        "address_data": <bindata for 1.0.0.1>,
        "address_type": <bindata of "IPv4">,
        "tls_auth_name": <bindata of "cloudflare-dns.com">
      }
    ]
  },
  "api_version_number": 132058112,
  "api_version_string": <bindata of "December 2015">,
  "compilation_comment": <bindata of "getdns 1.5.2 configured on 2019-"...>,
  "default_hosts_location": <bindata of "/etc/hosts">,
  "default_resolvconf_location": <bindata of "/etc/resolv.conf">,
  "default_trust_anchor_location": <bindata of "/etc/unbound/getdns-root.key">,
  "implementation_string": <bindata of "https://getdnsapi.net">,
  "listen_addresses":
  [
    {
      "address_data": <bindata for 127.0.0.1>,
      "address_type": <bindata of "IPv4">,
      "port": 5453
    }
  ],
  "openssl_build_version_number": 269488207,
  "openssl_built_on": <bindata of "built on: Sun Oct 20 22:14:07 20"...>,
  "openssl_cflags": <bindata of "compiler: arm-brcm-linux-uclibcg"...>,
  "openssl_dir": <bindata of "OPENSSLDIR: "/etc"">,
  "openssl_engines_dir": <bindata of "ENGINESDIR: "/usr/lib/engines-1."...>,
  "openssl_platform": <bindata of "platform: linux-armv4">,
  "openssl_version_number": 269488207,
  "openssl_version_string": <bindata of "OpenSSL 1.1.1d  10 Sep 2019">,
  "resolution_type": GETDNS_RESOLUTION_STUB,
  "version_number": 17105408,
  "version_string": <bindata of "1.5.2">
}
Result: Config file syntax is valid.