a=black-1.test.ex ${lookup dnsdb{a=black-1.test.ex}{$value}fail}
xxx=test.ex ${lookup dnsdb{xxx=test.ex}{$value}fail}
a=localhost.test.ex ${lookup dnsdb{a=localhost.test.ex}{$value}fail}
a=black-1.test.ex ${lookup dnsdb{a=black-1.test.ex}{$value}fail}
xxx=test.ex ${lookup dnsdb{xxx=test.ex}{$value}fail}
a=localhost.test.ex ${lookup dnsdb{a=localhost.test.ex}{$value}fail}