1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, 13 * software distributed under the License is distributed on an 14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 15 * KIND, either express or implied. See the License for the 16 * specific language governing permissions and limitations 17 * under the License. 18 * 19 */ 20 21 package org.apache.directory.server.dns.io.encoder; 22 23 24 /** 25 * 3. The DNAME Resource Record 26 * 27 * The DNAME RR has mnemonic DNAME and type code 39 (decimal). 28 * 29 * DNAME has the following format: 30 * 31 * <owner> <ttl> <class> DNAME <target> 32 * 33 * The format is not class-sensitive. All fields are required. The 34 * RDATA field <target> is a <domain-name> [DNSIS]. 35 * 36 * The DNAME RR causes type NS additional section processing. 37 * 38 * The effect of the DNAME record is the substitution of the record's 39 * <target> for its <owner> as a suffix of a domain name. A "no- 40 * descendants" limitation governs the use of DNAMEs in a zone file: 41 * 42 * If a DNAME RR is present at a node N, there may be other data at N 43 * (except a CNAME or another DNAME), but there MUST be no data at 44 * any descendant of N. This restriction applies only to records of 45 * the same class as the DNAME record. 46 * 47 * This rule assures predictable results when a DNAME record is cached 48 * by a server which is not authoritative for the record's zone. It 49 * MUST be enforced when authoritative zone data is loaded. Together 50 * with the rules for DNS zone authority [DNSCLR] it implies that DNAME 51 * and NS records can only coexist at the top of a zone which has only 52 * one node. 53 * 54 * The compression scheme of [DNSIS] MUST NOT be applied to the RDATA 55 * portion of a DNAME record unless the sending server has some way of 56 * knowing that the receiver understands the DNAME record format. 57 * Signalling such understanding is expected to be the subject of future 58 * DNS Extensions. 59 * 60 * Naming loops can be created with DNAME records or a combination of 61 * DNAME and CNAME records, just as they can with CNAME records alone. 62 * Resolvers, including resolvers embedded in DNS servers, MUST limit 63 * the resources they devote to any query. Implementors should note, 64 * however, that fairly lengthy chains of DNAME records may be valid. 65 * 66 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 67 * @version $Rev: 501160 $, $Date: 2007-01-29 20:41:33 +0100 (Mo, 29 Jan 2007) $ 68 */ 69 public class DnameRecordEncoder 70 { 71 }