report error if zone doesn't match

lib/index.js

@@ -14,6 +14,10 @@ module.exports.create = function(config) {
 			throw Error('listing zones not implemented');
 		},
 		set: function(data) {
+			var ch = data.challenge;
+			if (!ch.dnsZone) {
+				throw new Error('No matching zone for ' + ch.dnsHost);
+			}
 			// console.info('Add TXT', data);
 			throw Error('setting TXT not implemented');
 		},