Sergey

Вы не ответили на вопрос «как настроить такую схему?»

config 'interface' 'wan'
        option 'weight' '10'
        option 'health_interval' '10'
        option 'icmp_hosts' 'dns'
        option 'timeout' '3'
        option 'health_fail_retries' '3'
        option 'health_recovery_retries' '5'
        option 'failover_to' 'wan2'
        option 'dns' 'auto'

config 'interface' 'wan2'
        option 'weight' '10'
        option 'health_interval' '10'
        option 'icmp_hosts' 'dns'
        option 'timeout' '3'
        option 'health_fail_retries' '3'
        option 'health_recovery_retries' '5'
        option 'failover_to' 'wan'
        option 'dns' 'auto'

что раздел q&a как-раз создан для поиска конкретных решений

открыт порт 53/tcp

(прошло уже больше суток)

dig example.com SOA

Как его заставить писать логи? 

logging {
#	# Log queries to a file limited to a size of 100 MB.
	channel query_logging {
		file "/var/log/named_querylog"
			versions 20 size 200M;
		print-time yes;			// timestamp log entries
		severity dynamic;	
	};
	channel security {
		file "/var/log/named_security"
			versions 10 size 50M;
		print-time yes;
		severity dynamic;	
	};
	channel resolver {
		file "/var/log/named_resolver"
			versions 2 size 50M;
		print-time yes;
		severity dynamic;	 
	};
	channel network {
		file "/var/log/named_network"
			versions 2 size 50M;
		print-time yes;
		severity dynamic;	 
	};
	channel xfer {
		file "/var/log/named_xfer"
			versions 2 size 50M;
		print-time yes;
		severity dynamic;	 
	};
	channel client {
		file "/var/log/named_client"
			versions 2 size 50M;
		print-time yes;
		severity dynamic;	 
	};
	category queries { query_logging; };
	category security { security; };
	category resolver { resolver; };
	category network { network; };
	category xfer-in { xfer; };
	category xfer-out { xfer; };
	category client { client; };
#
#	# Log general name server errors to syslog.
	channel syslog_errors {
		syslog user;
		severity error;
	};
	category default { syslog_errors;  };
#
#	# Don't log lame server messages.
	category lame-servers { null; };
	category security { null; };
};