Can't make v2ray to send DNS queries to its localhost

There are two v2ray servers A and B with similar configurations but A works as an intermediary (vmess+websocket on both inbound and outboud) to reach B.

I want to make A to send incoming DNS queries to its localhost:53 where CoreDNS is listening on. How to do it?

I've done this in A:

...
    {
      "protocol": "dns",
      "tag": "dns_out",
      "settings": {
        "address": "localhost",
        "port": 53
      }
    }
  ],
  "dns": {
    "queryStrategy": "UseIPv4",
    "servers":["localhost"],
    "tag": "dns_inbound"}
  },
  "routing": {
        "domainStrategy": "IPOnDemand",
        "rules": [
            {
                "type": "field",
                "port": 53,
                "network": "tcp,udp",
                "outboundTag": "dns_out"
            }
        ]
  }
}

But why v2ray A always chooses the default route (of two routes: protocol vmess and protocol dns) and sends no DNS queries to CoreDNS on localhost:53?

The problem was an extra } where I specify tag for dns. And v2ray was fine with it, ignoring rest of it.